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51  General Politics / Political Geography & Demographics / Re: Recent developments in redistricting reform (April 2016) on: June 03, 2016, 11:09:06 am
North Carolina:

The federal district court (M.D. N.C.) has rejected the plaintiff's appeal with regard to the congressional remedial plan drawn by the legislature.

The court ruled that their jurisdiction was limited to determining whether the legislature had remedied the defect that the court had identified (high percentage of blacks in NC-1 and NC-12), which the remedy obviously did.

The plaintiffs argued that the legislature did not draw the plan that a court might have drawn, but that does not matter because the SCOTUS has ordered federal courts to defer to state-drawn plans.

The plaintiffs also argued that the remedial plan was a partisan gerrymander. The court did not want to adjudicate a new claim. It said that the plaintiffs could bring a new case.
52  General Politics / Political Geography & Demographics / Re: Augusta (mostly), ME census block/ward/house district boundary issues on: June 03, 2016, 02:21:20 am


You can display the direction of the lines in QGIS:

Right Click on Layer, Select Properties, Select Style.

In the second box you should see:

> ___ Line.

Click on the > to expand:

> ___ Line.

    ___ Simple Line

Click on the Green +

> ___ Line
   ___ Simple Line
   ___ Simple Line

Select one of the simple lines and select Marker Line (upper right)

Select Simple Marker, and then choose the > symbol

Apply.

To get back to the normal simple line, select the marker line and the red "-".

Select the lines corresponding to the three streets (Country Club Rd, Joel Ave, and Apple Tree Ln).

Make note of the TLID.

You can drag the addr.dbf file into the canvas. Make it the current layer. Select by Expression:

"TLID" = '75481176'  for example is Country Club Rd

Vermont and bring the selected features to the top. There should be four for Country Club Road. See the fields SIDE, FROMHN, and TOHN

Side is either L or R, for the left or right side of the road.

Right (east) is 53-79
Left (west) is 8-48, 56-60, 37-51

I don't see any addresses on the tax maps.

I suspect the three houses are enumerated based on the street edge rather than the location of the building.

What is the population and housing county for Block 1037?

A better boundary might well be the Augusta Country Club.
53  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: June 03, 2016, 12:22:00 am
Part 14

Exercise: The Census Bureau has proposed attaching the triangle formed by Columbia Street, Green Street, and State Street to Block 13-5009. This would move the block boundary off Columbia Street, which is Hudson's longest continuous street, and also a ward boundary since 1855.



The preferred alternative is to attach the triangle to 13-5010. This would cut off the last piece of State Street.

Exercise: Split the triangle from 13-5009 and merge it with 13-5010 to produce:



Exercise: The street dividing 13-4008 and 13-4009 does not exist and should be deleted. This will result in the two blocks being merged.



Exercise: Merge 13-4008 and 13-4009 to produce:



Exercise: Rope Alley (green line) is missing between N 6th Street and N 7th Street. Adding it will split block 13-5003. The red line within the block is spurious, and will be deleted.



Exercise: Split 13-5003 on Rope Alley to produce.



Note that both new blocks are numbered 13-5003. We will correct that in the next part.
54  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: June 02, 2016, 11:09:34 pm
Part 13

The next change is around the triangle formed by Columbia Street-Columbia Turnpike-Prospect Avenue



The tips of Prospect Avenue and Columbia Turnpike intersect just south of their respective intersections with Columbia Street. In addition, the census bureau has a bogus version of Columbia Turnpike connecting with Columbia Street on a north-south direct just to the east.

In 2010, there were two small census blocks. For 2020, the census bureau proposes adding the triangle to 13-4008 (prototype block number), and the bogus block to 13-4007.

Since we will delete the non-existent Columbia Turnpike connection, 13-4006 will extend further west. Columbia Turnpike is the ward boundary (and has been since 1855), so it is preferred that 13-4006 also contain the triangle.

We will first chop off the tips of 13-4008 and 13-4007, and then merge them with 14-4006.

We first select the line we wish to cut 13-4007 with in the Kevinstat layer.



We select the block (13-4007) that we wish to cut.



To actually split the block:



(1) Make sure the current layer is the one with the polygon to be split.
(2) Make sure editing is active for that layer, clicking on the pencil icon if necessary to toggle it.
(3) Click on the "Split selected features with selected line from another layer" tool.



(4) Make sure the correct splitter layer is chosen.
(5) Click OK

The block has been split.



The original block no longer exists - so it is not selected. The split line remains selected. The two new blocks take their attributes from the original block, so they are displayed with the same color, but are labeled separately (there are now two 13-4007 blocks).

We also need to split off the tip of 13-4008. We repeat the splitting process. This is what we see after the split has been completed.



We will now merge the two small blocks with 13-4006.



Select the blocks to be merged, to merge the blocks:



(1) Under Edit.
(2) Select Merge



(3) Select the block to take attributes from (it will be highlighted in orange)
(4) Click on Take Attributes From Selected Feature
(5) Click on OK



The two small areas have been split from their original blocks, and merged with 13-4006. Toggle editing to save the changes, and turn off all selections.
55  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: June 02, 2016, 10:12:57 am
Part 12

In this lesson we are going to edit the Prototype block boundaries. The Prototype file represents current Census Bureau intent for 2020. Our version is in essence our counter proposal incorporating all our changes.

We first make a copy of the prototype layer.



(1) Right Click on Prototype Layer, Select Save As.
(2) Select Browse then enter the file name of the layer (if you don't select Browse first and just enter a name, the files will end up somewhere you won't be able to find.
(3) OK.

We will be splitting blocks using lines from another layer. This explains how to do it.

QGIS lesson 26 – Splitting a polygon with lines from another layer (youtube)

The entire set of lessons can be found at:

Youtube Search: "Steven Bernard QGIS lesson"

The first should be:

"QGIS Uncovered"

And there is an item that says:

"View full playlist (31 videos)"

Click on that and you will have the full series available.

We first install the Digitizer Tools Plugin



(1) Click on Plugins
(2) Manage and Install Plugins



(3) Scroll down and select "Digitizing Tools"
(4) Install.

For reasons unknown, splitting a polygon with Digitizing Tools does not work when using projected coordinates. Both the census block and the edges are stored as LAT/LONG, but we have been projecting them because (1) LAT/LONG maps give me nausea; (2) We can't overlay them over the Google Map. The splitting works OK, but one of the resulting polygons is stored with projected coordinates. Since QGIS expects everything in the layer to be LAT/LONG the polygon is not displayed, and can not be graphically selected.



(1) Click on ICON in extreme lower right corner.
(2) Uncheck box for "Enable on Fly CRS transformation"
(3) Apply

We are now ready to begin editing.



(1) We have checked the box to display our blocks file. We have also set it to use a different color for each block, and to label with the block number.
(2) We have also checked the box to display our suggested lines.
(3) While the hudsonsuggestedblocks layer was selected, we clicked on the pencil icon To Toggle Editing. This enables editing of the layer - which is indicated by a small pencil on the icon next to the layer.  The pencil icon is a toggle. To disable editing, click on the pencil. You can also toggle editing for a layer by right clicking on the layer and click on Toggle Editing.

My practice is to do editing in small pieces. Toggle Editing on; Make the Edit; Toggle Editing off. You will be prompted to save the edit. If you have messed up, you can simply discard the edit.

(4) When you are editing, the icons for the Digitizing Tools are in color. When I installed the plugin, the icons were put on a 3rd row.  I dragged the vertical row of dots up to the second row.
(5) This is the icon for Splitting a Polygon.

Our first edit, will be to merge blocks 13-4003 and 13-4004. They are currently separated by a block boundary drawn through a church parking lot.



Select the blocks to be merged.



To merge the selected blocks



(1) In the Edit Menu
(2) Select Merge Selected Features

The following table will pop up.



(1) Select a block to take attributes for the merged block. It will be highlighted as orange.
(2) Click on Take Attributes from selected feature.
(3) Click on OK.

We are overloading Block Number. Is Block 4003 the original block or the merged block? Since we are mainly interested in display, it doesn't matter too much. I chose 4003 because it is the larger portion of the merged block, and also because it is a lower number.

The blocks have been merged.



The colored lines are from the kevinstat layer. You can confirm that the block is whole by selecting it.

Click on the Pencil to Toggle Editing for the layer.  You will be prompted to save the change.
56  General Politics / Political Geography & Demographics / Re: Augusta (mostly), ME census block/ward/house district boundary issues on: June 02, 2016, 06:52:41 am
Quote from: Amanda Rector to me on Wednesday, May 25, 2016 at 9:22 PM

...
For the Gardencrest area in Manchester, it looks to me like the Census Bureau had misaligned the boundary, which resulted in the three houses being cut off from the rest of the block. I have suggested that the property boundary of the golf course (as close as I can figure, at least) be the corrected boundary. This would move those three houses back into the block with the remaining Gardencrest neighborhood.
...

Quote from: Me to Amanda Rector on Wednesday, May 25, 2016 at 9:26 PM
...
I think the Census Bureau may have been using power lines (the kind that go through the woods) as a block boundary in Gardencrest, but you're right that it was misaligned in areas (particularly when you get toward Readfield/Winthrop in I think the apple orchard), although those three houses were on the other side of them from the rest of the neighborhood.  But I am happy that boundary is removed.  Using the golf course boundary as a block line might keep homes on the fire road coming from what used to be Cobbossee Cash Market (where you have to leave Manchester to go anywhere else in town) in a separate block from Gardencrest, which might have been part of the Census Bureau's motivation for having a boundary in that area in the first place.
...

Does the power line cut a street?  You might want to check the .addr.dbf file.  In Hudson, some of the TO-FROM addresses were completely messed up in the 2010 Census edges file, but had been corrected in the partnership .addr file.

I don't know if this had been messed up during the 2010 census, or it had been caught at that time 2010, but not found its way into the census maps.
If you zoom in really closely on the Google areal map you can see the trio of power lines.  It crosses US 202 (called "Route 202" in Maine if not by some street name, like Western Ave. in Augusta west of the west side rotary) between the two entrances to Fairway Overnite & Extended Stay, goes just west of the various buildings in the lot (I think the one in the back may be the owner's family home) and crosses over the corner in of the dead-end portion of Country Club Road (what Google Maps still has as both Country Club Rd and Joel Ave which used to be the name of that dead-end portion).  I've stood at that corner around noon and the power lines (at least the middle one) doesn't quite touch the center line even if you assume the center line doesn't curve where the inside of that corner curves (Google's satellites have it off a bit in the other direction from the Census Bureau), but it is closer to that center line than to the outside corner of the pavement.  If the power lines were aligned properly, there would probably have been an additional 2010 and 2020 prototype block in Gardencrest as Joel Ave from that corner to the intersection with Apple Tree Lane (it's never Apple Tree Drive or Appletree Drive) and the beginning of Woodridge Drive would divide the outside of Gardencrest (or the portion east of the power lines) on either side of the two interior blocks.  Both interior blocks would border both exterior blocks (east of the power lines) in that case, allowing for a snaking legislative district boundary (a very unlikely one but it would be possible).

Going north and west, the Census Bureau's line starts to go a bit east of the power lines, but then cuts hard to the west until it ends on the Manchester-Winthrop town line.  Another line begins just north of where the power lines cross into Wintrhrop, seemingly an attempt to follow that same set of power lines (it has the symbol for a pipeline or power line on 2010 census block maps; see http://www2.census.gov/geo/maps/dc10map/GUBlock/st23_me/county/c23011_kennebec/DC10BLK_C23011_014.pdf ).  But there isn't an approximation of the power lines between Case Road and (almost) Carlton Pond Road.  That may be because the Census Bureau's ... whatever they have that makes the lines acted as if the power lines stopped at Case Road and that a new set of power lines started a bit further west (see that same link above).  But given that the Census Bureau is trying to cut down on the number of census blocks, I would have thought those power lines (that weren't a block boundary for the 2000 census, at least around Gardencrest) would have made sense not to be block boundaries, as from reading what you have written is the norm (power lines not being block boundaries) elsewhere in the country.

I'm not sure how I'd go about checking the .dbf file (or even what to open it with).  You might have covered that in your recent tutorials (I haven't done anything since Part 7).  By .addr.dbf did you mean PVS_15_v2_addr_23011.dbf ?  I've been more focused on trying to get the lines right than where the Census Bureau counts people (improving the first ought to make the second easier and more intuitive, like if the eastern boundary of the Howard Hill property was a block line instead of "Waddington Street" to borrow from another of my areas of focus).
I'm having a hard time following you.

This is the area of concern?



I am displaying the 2010 census blocks and Partnership edges file. Is the problem that block 1035 (the green one) wraps around the other two blocks. Where are the power lines?  I see what looks like a power line cut through the woods on the south side of Western Avenue a bit to the east in block 2010.


57  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: June 01, 2016, 09:26:10 am
Part 11

We can use complex expressions to control the display for analytical or presentation purposes:



(1) Right click on the layer and select Properties.
(2) Select Style.
(3) Select Categorized.
(4) Click on the Script E, to enter an expression. In this case we create a combination of the tract and block number. Census tract numbers are 6 digits, with an implied decimal point after the fourth digits. Conventionally, leading zeroes and fractions of .00 are suppressed.

001200 is displayed as "12"
001201 would be displayed as "12.01".

Since we know that the Hudson census tracts have no fraction, we can use a simplified expression to extract the tract number. We then append a hyphen (literal '-') and the block number. The || is the concatenation operator.

(5) We select a random color ramp.
(6) A click on classify. QGIS searches through the tables and creates a category for each unique value and assigns a color - because the color ramp is random, the colors assigned are random.
(7) We can also Delete All Categories. For example, if we have classified already, and then change our expression for classification, we can delete our current categories. Or if we change a value we are classifying on, we can simply click on the Classify, and any new classes will be added.
(8) Click on Apply.

We can also add labels.



(1) Right click on layer select Properties.
(2) Select Labels.
(3) Select Show Labels for this Layer
(4) Select Script E and enter expression for labels.
(5) Select Text
(6) Select Parameters for labels.

For our purposes right now, the default values are fine.

(7) Apply.

We can select/deselect which categories we want to display, with the check boxes.



In this case, our category is block number, so we are disabling display of certain blocks. One could imagine a map of Maine where towns were categorized by population. You could then choose to display towns with populations between 1000 and 2000, for example.

You can change the color of a category by right clicking on the color square.

In this case we selected the blocks that would be changed if our suggestions were accepted. We also changed the color of blocks that would be merged if the existing block boundaries were eliminated - either by deleting the line, or changing it to a not hold. For example, the three blocks in the Hudson Correction Facility can be merged. There are a total of six mergers, eliminating 7 blocks.



We can use complex expressions to control display.



Quote from: QGIS expression
left(  "JUSTIFY" ,2) || 
"CHNG_TYPE"  ||
if( "CHNG_TYPE" ='AL',
    if( "BBSP_2020" =1,'+',''),'')||
if( "CHNG_TYPE" ='CA',
    if( "BBSP_2020" =1,'+',''),'')

This expression combines values from three fields. JUSTIFY is a 150-character field to express justification for a suggested change. I included a two-digit number for each change.

CHNG_TYPE is either 'AL', 'CA', 'DL' for Add Line, Change Attributes, Delete Line.

BBSP_2020 is a 1 if he want to hold a line as a block boundary. If an added line is intended to be a block boundary we add a '+' to the category. If an existing line is to be held as a block boundary it is flagged with BBSP_2020 (in some cases, it is the flag that is the changed attribute).

Below the expression is an example output.

This shows some of the categories.



Here we do a little bit of label formatting.



(1) Right Click on layer, select Properties.
(2) Select Labels
(3) Select Show Labels for this Layer
(4) Click on Script E to enter Expression. In this case, we are displaying the leftmost two characters of JUSTIFY.
(5) Select Text
(6, 7, 8) Select Font, Select Bold, Select Size

For right now we just want some numbers to help us find the changes.

(9) Apply Changes.

This produces this rather raw looking map.



I then selected suggested items with a particular theme, in this case deleted lines which had no impact on block boundaries. Rather than doing a screen dump, I saved an image of the canvas:



(1) Select Project.
(2) Save as image.

This will save a .png image, as well as a .pngw file. The .pngw file describes the coordinates of the image, so that one could reload the image at a later time.

This image could be used as part of a presentation to those who would be reviewing the suggestions, whether local officials or the redistricting liaison. The numbers would provide a reference to text explaining what each feature represents, and why it is being removed.



58  General Politics / Political Geography & Demographics / Re: Most contiguous complete counties in a Congressional District on: June 01, 2016, 07:35:48 am
Here's how this works:

  • Post a Congressional District with as many complete contiguous counties as you can.
  • The district has to be drawn in such a way that all other districts in the state can be drawn contiguously. For example, this is why I did not include some low population counties along the Rio Grande river in my initial map below.
  • Population deviations of up to about 5,000 are acceptable.
  • You can either post a district with a greater number of contiguous complete counties than a previous poster, or post a district for a new state that nobody has done yet.
  • You can have left over population in a partial county, but the county split doesn't count as a county. In other words, you have to round down your number of counties to the nearest whole number.
  • Post some basic demographics about the district.

I started with Texas because it has so many counties, including many sparsely populated ones in West Texas. But it might be possible to do get a greater number of counties in one of the plains states (?). This has 92 counties, but I didn't really optimize it. You could probably improve on it by explicitly counting the populations in each county to make sure you include all the smallest ones.



Stats:

92 counties

Population 700,961 (+2,473 deviation)

53.3% White
42.5% Hispanic

27.6% Obama
72.4% McCain

There is a surprisingly large number of Hispanics, and yet it is so Republican!
Remove Runnels, Callahan, Pecos, Moore, and Hockley

Add Concho, Archer, Coleman, Blanco, Live Oak, Karnes, Goliad, Refugio, and Comanche.

If you could population for two districts from El Paso to Amarillo (going through Culberson, Reeves, Ward) that could be split off from the remainder of the state, this would permit the eastern part of the state to be split off from the western.

You could also remove Hutchinson and Jones, and perhaps add 3 counties elsewhere.

The theoretical limit disregarding contiguity is 111 counties (Zapata 14,018 or smaller)
59  General Politics / Political Geography & Demographics / Re: Most contiguous complete counties in a Congressional District on: June 01, 2016, 06:43:05 am
I love this - what is the biggest city in that district? San Angelo?
Tom Green is the county with the panhandle.

I think the largest city is Pampa.
60  General Politics / Political Geography & Demographics / Re: Augusta (mostly), ME census block/ward/house district boundary issues on: June 01, 2016, 06:05:42 am
Can anyone verify (or refute) that a redistricting liaison can make additional changes (not just clarifications to something the liaison had made some note about but perhaps not in the right way, but something where nothing had been done in the initial phase) in the verification phase?  With her comments on the Bridge Street area, I'm not sure if Amanda meant that she hadn't even added the extension of North Street (a current ward boundary) as a must-hold line, or if she just hadn't been able to add the additional line I was suggesting - I hadn't communicated a decent place for that line to end on the end other than Bond Brook until just last week which I pretty much knew was too late for this phase of the project.

Also, can the voting districts in the Voting District Project phase of the Redistricting Data Program split the blocks that result from the Block Boundary Suggestion Project phase?  I had assumed they couldn't.  But Amanda's latest message to me suggests otherwise.  Perhaps the Census Bureau would just divide a block into two or more blocks in that case.

I don't think there's much chance the Augusta City Council will want to move the Ward 1-Ward 2 boundary west of Sewell Street, so I found the ward boundary justification for holding the existing boundaries along "Waddington Street" (while getting rid of that street as a street) a little odd.  It might not have mattered, though, since the boundary between the "southwest Sewall blocks" and the "big honking Howard Hill block" as they existed in 2010 is the current (legal) boundary between House Districts 85 and 86.  Amanda's must-hold line (lines probably) there might be helpful actually as they will draw attention to that area and when someone sees a must-hold line going through a condo (the Murdock condo), there could be some follow-up that could result in a better line.

I'm glad the outside of Gardencrest will all be in one block, although I'm not sure the golf course boundary was necessary.  I hadn't made it clear, in re-reading my e-mail where I first mentioned Gardencrest, that the three homes in the other block from the rest of the outside (not in the two loops) of the neighborhood were indeed on the other side of the power lines from the rest of the neighborhood.  Those power lines (if that was indeed what the Census Bureau thought they were following as a block boundary) were pretty badly misaligned further north, although it didn't look like any homes in Manchester were impacted.  In my reply, I did mention that her golf course boundary might result in Gardencrest (now all of the outside instead of missing those three homes) remaining in a separate block from homes further west where it might make sense for them to be in a separate census block.  But that depends on if you just go around the golf course or somehow connect with the prototype block line following (roughly) the power lines.

I was surprised at all of Maine's township lines becoming block lines.  That will result in a decent increase in the number of blocks (3 more apiece for most 4-corner township intersections probably).  I wonder if the fact that the person who seemed most upset at how the boundary between House Districts 150 and 151 was interpreted was a former longtime Speaker of the House (still quite influential, I believe) had anything to do with that?  I didn't think to ask Amanda if that included the Penobscot Indian Island Reservation, which includes islands in the Penobscot River from Old Town to Medway.  Department of Transportation and DeLorme maps (when DeLorme existed) have that area parceled off among the various towns on either side of the river.  While it probably would have worked numbers-wise to parcel off the part of the Penobscot Reservation north of what the DOT and DeLorme considered Old Town into other districts (several of which crossed the river and were thus arguably not contiguous the way the lines were drawn), as has been done in the past, the entire area of the reservation was kept in one district, which made me wonder if some federal law were at play that people finally noticed in 2013.
In previous censuses, the block boundary suggestion project and the VTD project were conducted at the same time. The states specifically requested that they be split.

2010 was the first time that VTD boundaries could split block boundaries - that the VTD boundaries could force splits of blocks on artificial lines. My understanding would be that you could identify non-traditional block boundaries such as streams, power lines, ridge lines that could be used as block boundaries during the first phase; but totally artificial lines such as are used in Hudson would have to wait to the second phase.

This presentation 2020 Census Redistricting Data Program (PDF), by the Census Bureau to the NCSL suggests that block changes can continue to be suggested throughout the process. Note that 2016 is pretty early to be finalizing geography for the 2020 census.
61  General Politics / Political Geography & Demographics / Re: Augusta (mostly), ME census block/ward/house district boundary issues on: June 01, 2016, 05:35:58 am
Quote from: Amanda Rector to me on Wednesday, May 25, 2016 at 9:22 PM

...
For the Gardencrest area in Manchester, it looks to me like the Census Bureau had misaligned the boundary, which resulted in the three houses being cut off from the rest of the block. I have suggested that the property boundary of the golf course (as close as I can figure, at least) be the corrected boundary. This would move those three houses back into the block with the remaining Gardencrest neighborhood.
...

Quote from: Me to Amanda Rector on Wednesday, May 25, 2016 at 9:26 PM
...
I think the Census Bureau may have been using power lines (the kind that go through the woods) as a block boundary in Gardencrest, but you're right that it was misaligned in areas (particularly when you get toward Readfield/Winthrop in I think the apple orchard), although those three houses were on the other side of them from the rest of the neighborhood.  But I am happy that boundary is removed.  Using the golf course boundary as a block line might keep homes on the fire road coming from what used to be Cobbossee Cash Market (where you have to leave Manchester to go anywhere else in town) in a separate block from Gardencrest, which might have been part of the Census Bureau's motivation for having a boundary in that area in the first place.
...

Does the power line cut a street?  You might want to check the .addr.dbf file.  In Hudson, some of the TO-FROM addresses were completely messed up in the 2010 Census edges file, but had been corrected in the partnership .addr file.

I don't know if this had been messed up during the 2010 census, or it had been caught at that time 2010, but not found its way into the census maps.
62  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 31, 2016, 07:14:11 am
Part 10

Since we are concentrating on Hudson, we can eliminate the rest of Columbia County.



(1) We will be using the census tracts layer for clipping. Hudson is entirely in Census Tracts 12 and 13, and Census Tracts 12 and 13 are entirely in Hudson. For simplicity display of all layers but the census tracts has been turned off.
(2) Select graphically by freehand.
(3) Select census tracts 12 and 13.

(4) Select Vector, Geoprocessing Tools
(5) Select Clip.

Clip keeps what is in the selection layer, Difference removes what is under the selection layer



(6) Select the input layer (when you click on the little arrow, you will get a list of layers to select from)
(7) Select clipping layer.
(Cool Be sure Use Only Selected Features is checked. This is the default when there are selected features.
(9) Click on browse, make sure that you are in the correct directory, and enter the name of the output layer.
(10) Make sure add result to canvas. This isn't necessary, and if you were doing this on a batch basis you might turn it off. But it is a good idea to check.
(11) Click on OK.  The progress bar will move across as the processing takes a few seconds.



If you check your directory you will see a whole suite of new files (.shp, .dbf, etc.).

I did a few additional steps:

(12) Right click on the original layer, and select remove, and confirm when prompted. This will reduce the clutter, and avoid editing a source file. Even if I weren't clipping, I would do a Save As to make a copy. I might also do this if trying some new feature in QGIS.
(13) Right click on the Hudson-limited layer and select Show Feature Count. There are 2680 blocks in Columbia County, and 121 in Hudson.
(14) Pan to Layer, so that canvas is centered on Hudson.

Repeat the same process to produce

hudsonpartnertabblock2010 {faces, tabblock, edges}
hudsoncensusfaces {edges}

Note, the census tracts will remain selected unless you unselect them, so that part can be skipped.
63  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 30, 2016, 10:03:25 pm
The file PVS_15_v2_addr_36021.dbf does have the address ranges. It can be opened in Excel. You can  also drag it to the map area - you can look at the parameters, but I have not figured a way to search it. I ordered it by TLID and then scrolled down to 640427671. In Excel, I can search for 640427671.

There's still no way to save changes to a .dbf file in Excel, correct?  I always have to use OpenOffice to do the final step in merging my data when making an election map.  Can QGIS do something to merge tables (like, one .xls or .csv and the original Census .dbf)  that I haven't figured out how to do in MapWindow GIS?
I think Excel is part deliberate policy. If you want people to migrate to Office you provide one way conversion.

Yes, you can do a join.  That is how I did this map:



When I do redistricting, I do it in a spreadsheet. Starting with a population spreadsheet, with a row for each county, town, or block. I calculate the normalized population for each (share of a seat), and have a column for district number.

I use SUMIF to calculate the population of each district. So I just change the district number for a block, etc. to move it to a new district.  In olden days I would then use Paint to draw the map.

But now I save the parts of the Excel file as a CSV file, and join it to the census shapefile (actually a copy of it). For the map above, I added columns with the block population and the ward the block was assigned to. After the join, I used the block population for block label, and the assigned ward for the block color.

You can also do a merge operation. In a case like this, I would merge all the blocks with the same ward number to create a ward layer. I can then overlay the ward layer over the block layer:



In this case, I also put the total ward population in each block row so it carried over into the row for the (merged) ward. I probably could have calculated the total population in QGIS, but it was easy enough to do it in a spreadsheet.
64  General Politics / Political Geography & Demographics / Re: Prison population and the census on: May 30, 2016, 09:25:04 am
Is there an easy way to determine the population and demographics of counties minus their prison populations.  I'm specifically interested in the CAPP coal region--Eastern Kentucky, South WV and SW Va.  Besides state prisons, there tends to be a large number of federal prisons located in the region.  Is there any census filter that pulls out the incarcerated?

GROUP QUARTERS POPULATION BY GROUP QUARTERS TYPE

There are some subtables that pull out numbers by race, age, or sex.

Boyd County, Kentucky had a federal prison with 1515 inmates:

671 non-Hispanic White.
646 black
14 American Indian
12 Asian
197 Hispanic

This totals to 1540, so must be 25 black Hispanics.
65  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 30, 2016, 08:54:41 am
Part 9

Let's load some more shapefiles:

_edges_
_block_ (prototype)
_faces_
_tabblock_
_tabblock2010_
_tracts2010_ (there is also curtracts, but in Columbia County it is the same)



Slide the layers around to match this order. Change the style for the area files. About half way down there is a layer transparency slider, slide it over about half way. All the way to the right is totally clear, all the way to the left is totally opaque. You may want to tone some of the colors down a bit.

We can still make kevinstat the current layer even thought it is not displayed. This lets us Pan to Layer which brings Hudson into focus.

Slide the edges layer below the faces layer, and set the style for the edges layer to be color red (leave the width minimal). Check box only the faces and edges file.

If you select another layer and then Pan to Layer, you will pan to Columbia County.



You can see where there are edges inside faces. Check off the box next to the edges file and then check it back on. This will help you see the edges that don't match faces.

Reverse the order of the edges and faces layers.

An edge is a polyline. A face is a closed polygon bounded by edges. Every face is bounded by edges. So when we put the edges on top, we can't see the faces.

Now put the edges layer back under the faces layer. Not every edge bounds a face, so we can see the edges that are not coincident with the faces.



Select the line shown (I've thickened the edges to make them more visible, and changed the color of the faces for more contrast). The line corresponds to State Street between N 3rd Street and N 4th Street.

(1) Be sure the edges layer is the current layer.
(2) Click on the pencil. This makes the layer editable. We aren't going to do any editing, but it necessary for the next step.
(3) Select the line. Notice the hatch marks. They correspond to the vertices of the polyline. Straight streets only need two vertices - this street has a third vertex near the middle of the block. Do a Control-C to copy the line to the clipboard.  Click on the pencil. If it asks about saving changes, say NO. If you didn't make any changes, you won't be prompted.
(4) Open up notepad and Control-V to save a copy of the line.

Quote from: TLID 640427671
wkt_geom   STATEFP   COUNTYFP   TLID   TFIDL   TFIDR   MTFCC   FIDELITY   FULLNAME   
SMID   SMIDTYPE   BBSPFLG   CBBFLG   BBSP_2020   CHNG_TYPE   JUSTIFY   LTOADD   RTOADD
   LFROMADD   RFROMADD   ZIPL   ZIPR   EXTTYP   MTUPDATE
LineString (-73.78705300000000022 42.25238099999998553,
-73.78799599999999259 42.25307399999999092,
-73.789551000000003 42.25422499999999104)   
36   021   640427671   211838163   261237232   S1400   Y   
State St   3271   A   4   4      
                        N   2013-04-05

Of particular interest are the vertices of the line. Census coordinates are stored as lat/long values with 6 digits to the right of the decimal point (storage is more precise than the actual measurement).

-73.787053 42.252381  
-73.787996 42.253074  
-73.789551 42.254225  

The first vertex is to the east and south, and the third vertex is to the west and north. So the line is encoded from N 4th Street to N 3rd Street. The second vertex is 38% of the distance from N 4th Street to N 3rd Street, so slightly closer to N 4th Street, which matches the graphical representation.

The TLID is new. TLID are assigned uniquely in the USA and are permanent. The original IDs in Hudson are around 4 million. New IDs are around 640 million. There used to be a (false) connection from Rope Alley to State Street. This was not used as a block boundary but did exist as a statistical line, and was removed. It would have forced State Street between 3rd and 4th Street to be encoded as two lines. Now that they can form a single line, the old TLIDs have been retired, and replaced by the new number.

Since the line has direction (from 4th Street to 3rd Street), it has a left and right side. If you open up the table, you will see that the line is indeed State St, and that the face to the left (TFIDL) is 218838193 and to the the right (TFIDR) is 261237232. There are also places for address ranges for the left and right sides of the street. The Census Bureau has not included them, but an update could include new addresses.

The file PVS_15_v2_addr_36021.dbf does have the address ranges. It can be opened in Excel. You can  also drag it to the map area - you can look at the parameters, but I have not figured a way to search it. I ordered it by TLID and then scrolled down to 640427671. In Excel, I can search for 640427671.

At any rate, addresses on the left side range from 399 to 301, and on the right side from 400 to 300, which is somewhat expected. Ordinarily 400 would be east of 4th Street, but 4th Street ends at State Street. 400 State Street is the former Hudson Area Library, and prior to that an orphanage and insane asylum. With the address ranges, we can convert from a street address of a census form, to a block number, so the people are enumerated in the correct block. The Census Bureau prefers to have streets for block boundaries, because they are then more likely to correctly map street addresses to blocks.

Not all edges form the boundary of a face, since they do not form part of a closed path. In those instances, the same face is on both the left and right sides.



In this map, the edges layers is classified based on:

   "TFIDL" = "TFIDR"

A value of one (true) indicates that the left face and right face are the same. A value of zero (false) indicates that the they are different. Thus the edges in red are in effect loose ends, streets, etc. that dead end, etc. that they don't form part of a closed path.

Incidentally, if you right click on a layer, and select Show Feature Count, it will show number of features for that layer.

Columbia County has 20,590 edges; 5,080 faces; and 3,878 census blocks (2010).  The prototype has 2680 blocks, a reduction of 31%.

We can also look at the faces.



Here we have selected the two faces on either side of State Street. As before, we click on the pencil to enable editing of the layer. Control-C to copy the contents of the selected faces, and paste into Notepad. Remember to click on the pencil to disable editing.

The  faces layer is displayed with a very transparent blue. That is why the haze clears as you travel over to Athens (across the Hudson River) in Greene County.

TFID 211838163, the face on the left side of State Street, also bounded by N 3rd Street, Long Alley, and N 4th Street has 6 vertices (with the first and last duplicated). TFID 261237232, the face on the right side has 20 vertices (19 unique). The northern edge is a statistical line. I suspect that the line was "created" in 1980 as a way to create a block in the area. In some Hudson GIS maps it is labelled as Clinton Street.

Census blocks are comprised of one or more faces. Thus the face could be a census block, but won't be because of the bogus statistical line.

Clicking on Vermont lets us see the attributes of the two faces. Census blocks are used as an atom for enumerating the census. Block groups, census tracts, places, MCD, school districts, legislative districts, urbanized areas, etc. are simply aggregations of blocks. The reason VTDs conform to block boundaries, is so that the census bureau can calculate the population of the VTD.

Since blocks are comprised of one or more faces, then a face can be part of every unit that a block is, and also part of the block. The face to the north of State Street is part of Census Tract 12, Block 1000.

I have added two additional shapefiles from the 2010 Census:

tl_2010_36021_edges
tl_2010_36021_faces

Tiger Products

Click on TIGER/Line Shapefiles, the first Product in the Green Table
Then 2010 in the blue table
Download, and then for the edges: Web Interface
Say 2010 again and "All Lines", which is toward the end of the list. Select the state and county, and download.

For the faces, back-up and select FTP Interface
Select FACES directory and then download the zip file based on the state and county codes of 36021 (36 = New York, 021 = Columbia County).

This compares the faces shapefiles for 2015 (partnership) and 2010 (Census)



You can see that in 2010 there were more faces than in 2015. You can see a similar result if you compare the two edges files (thicken the lines, and choose bright colors). For 2015, the box around the Hudson Correctional Facility was added, and the road to the east was more closely aligned with the satellite image. Otherwise, the 2015 file has some edges removed. These appear to be mainly pencil slips from the past. I suspect that before the 2010 Census, the Census Bureau started hunting for some "streets" and couldn't find them. They were converted to statistical lines, and then deleted after they weren't used.

This compares the 2010 faces to the 2010 blocks. There were faces that had been created by pencils that had slipped that weren't used as blocks, but there were also lots of blocks created by driveways and lanes in cemetery. And they didn't use the railroads as block boundaries as they had in 2000.



And finally we compare the prototype blocks to the 2015 faces.



In essence what we are suggesting is a counterproposal to the census bureau's prototype blocks.

(1) Delete edges corresponding to extraneous or non-existent features. This will eliminate some faces, which will cause some blocks to be merged. In other cases it will simply be removing digital debris.
(2) Correct placement of some streets. In two instances, they will form edge boundaries, and be usable as block boundaries. In other cases it makes the map match reality.
(3) Add missing features. In most cases these will be used as block boundaries.
(4) Indicated preferred must hold or must not hold which will modify block boundaries.
66  Presidential Elections - Analysis and Discussion / 2016 U.S. Presidential Election / Re: Will this shocking new evidence help Hillary/hurt TRUMP? on: May 30, 2016, 08:44:53 am
Guys, I recently found this information on google images while trying to help a new friend I just made.  Does this help Hillary steal votes away from supposed "man of the people" Donald Trump?




Where do they serve square pizzas on red plastic trays?  Wouldn't the pizza melt the plastic?
67  Presidential Elections - Analysis and Discussion / 2016 U.S. Presidential Election / Re: Washington Primary results thread (both parties; “polls close” at 11pm ET) on: May 30, 2016, 08:26:56 am
IIRC Washington tried to switch to a primary and the DNC werected the ones who got in the way - hence the beauty contest.
I thought that Washington Republicans pushed for a March primary for both sides and the Dem SoS opposed it for some reason to the point that Op-Eds in major newspapers in Washington State were calling to voters to vote just to send a message to the SoS so that Washington State could actually be the first West Coast state and largest Western state to have a primary where we could actually have a voice in national elections, where usually the West Coast is last to vote?
The SOS in Washington is a Republican and was pushing for a March primary.

The Washington Democratic Party apparatchiks opposed it.

68  Presidential Elections - Analysis and Discussion / 2016 U.S. Presidential Election / Re: Washington Primary results thread (both parties; “polls close” at 11pm ET) on: May 30, 2016, 08:21:53 am
IIRC Washington tried to switch to a primary and the DNC were the ones who got in the way - hence the beauty contest.
The Washington presidential primary was created by the initiative. At the time, Washington was still voting mostly in person. Washington voters DO NOT like having to publicly reveal their partisan affiliation. But the national parties require it. With a separate presidential primary, voters could grudgingly ask for a party ballot.

Under vote by mail, voters must complete a party affiliation form when they return their presidential ballot. They don't have to do that for other elections. One reason turnout was low is that voters did not want to complete that form, particularly as they saw the contests already having been decided.

In 2004 and 2012 the presidential primary was suspended. And in other years, the Washington Democratic Party ignored the results. So voters had another reason not to participate - not only did they have to sign a form, the Democratic party would still go ahead and dump the ballots in Puget Sound.

In 2015, the odd couple, SOS Kim Wyman and Senator Pam Roach, proposed a bill that would change the primary to March, and require at least one delegate be chosen based on the primary results. If both parties agreed, then party affiliation would be required, and both parties could even devise their own affiliation form. If both parties did not agree to binding, then the presidential primary would be a pure beauty contest with no party affiliation required.

The bill passed the Republican-controlled senate, but hung up in the Democratic-controlled House. At the committee hearing, a couple of Democratic Party officials testified (they appeared to either be longshoremen or from the teacher's union). They claimed that caucuses were more representative of the party workers, and besides the DNC wouldn't let them split their allocation of delegates between the caucuses and primary.

IOW, the DNC won't let us do what we don't want do.

The current presidential primary permits the primary date to be changed. But it has to be approved by a committee composed of the SOS, 2 legislators from each party, and 2 party officials from each party. Any change requires supermajority approval.

SOS Wyman and the Republicans voted yes to a March date.  The Democrats voted nyet, so the primary date remained in May.
69  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 29, 2016, 12:57:24 pm
Part 8

It is also possible to do selection by expression.



(0) I have switched the Style for the layer back to red for all values. This is simply to show what is happening better, and has nothing to do with the selection per se.

(1) Click on the Selection by Expression icon (Yellow icon with script E for "expression"). This brings down an expression builder box. You will see this in other places, for example you can build expressions for controlling style or building labels.

You can type into the box or use the menu at the right to select pieces of expression. Since the left box is essentially text that is parsed on the fly, you might want to create complex expressions in something like Notepad or Excel, and then just cut and paste into the left box. Or if you like an expression, you can copy it somewhere else.

I generally only use the right box to find field names and sometimes search for functions.

(2) In the right box click on the > next to Fields and Values, which will open up the list of fields, scroll down to CHNG_TYPE and double click on it, which cause it to appear in the left box. References to fields are surrounded by double-quote marks.

You will notice that below the left box there is a sample expression value. CHNG_TYPE is a text value and one of the rows has a 'CA' in it.



(3) Continue to enter the rest of the expression:    = 'DL'

You could click on the "=" sign above the box, but I find it easier to use the keyboard. Literal values are enclosed in single-quote marks. As you type, the expression is continuously being parsed, so there will be an error until you enter the closing single-quote mark.

(4) With the pull down menu, click on Select.

This  will select features where   "CHNG_TYPE"   = 'DL'

That is, those features where the value of CHNG_TYPE equals 'DL'

We have selected the features to be deleted.



We can select within selections. Our current selection is features to be deleted. We want to find the railroads to be deleted. Railroads have an MTFCC that begins with 'R'.



(1) We Select by Expression.
(2) We want to use a string function, so we click on the  <  next to String
(3) We double click on  left  which copies it to the expression box, and adds an opening parentheses.

The left() function has two arguments, a string and a length. We want the first character so we want an expression of:    left("MTFCC", 1)

We continue to build our expression.



(4) Double click on MTFCC to add it to the expression.
(5) Type in the remainder of the expression.

The left box is ultimately a free-form text, so we can click on it to set a text entry cursor. For example, if we looked at the expression and realized that we wanted to select features that are not railroads, place the text cursor in front of the =  ; press the Delete key, and enter  <>; or place the text cursor after the  = and use the backspace.

(6) In the pull down menu, click on Select within Selection.   The other options of Add to Selection or Delete from Selection may also have applications.



This shows the two railroads that should be deleted: the railroad to the cement plant across South Bay, and a rail siding. The tracks have been physically removed. Their former presences lives on in the census database.

We could have also did the selection with a single expression:

70  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 29, 2016, 05:38:33 am
Part 7

We can do more advanced displays:



(1) Right click on the layer and select Properties.
(2) Select style.
(3) Select Categorized.
(4) Set CHNG_TYPE as the field to classify on.
(5) Click on Classify.  It will produce a category for each unique value of CHNG_TYPE.
(6) Right click on each symbol (the line) and change color (red for DL, green for AL, blue for CL)
(7) Click on Apply



Once we have set up the separate categories, we can select individual categories.



(1) Uncheck all but 'AL'.  Selection is now limited to those categories. Do a graphical selection.


71  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 29, 2016, 02:25:26 am
Part 6

We are going to do a graphical selection. There are four types of graphical selection. One is a single click - more useful for selecting areas rather than lines; and three ways of selecting by area: polygon, circle, and free form. I find free form the most flexible, and can also be used for selecting multiple areas.



The pulldown menu lets us choose the selection method. Once selected, it remains the selection method. Once set, to make another selection click on the icon (without pulling down the menu).



With the cursor positioned, hold down the left mouse button, and lasso the area you want to select (in this case the orangeish area surrounding the Hudson Correctional Facility at the bottom of the map.
Release the mouse button and you should see:



Note in lower left the number of features you have selected. Selection is by intersection. You can select a single line by simply stroking with the cursor across it. However, what looks like a single line may be multiple lines connected end-to-end, so be sure to get all the parts of what you want.

Now we are going to look at the attributes of what we have selected.



(1) Click on the Vermont Avenue icon.
(2) At the top of the table click on the icon that has a yellow bar and a blue arrow. This brings the selected features to the top of the table - highlighted in blue. You can click on a column header and the features will be sorted. You can slide the columns about - which I did just to highlight the more important ones.
(3) More significant columns:
STATEFP: State code.

COUNTYFP: County code.

TLID: Permanent line ID (for the entire USA).

MTFCC: MAF/TIGER Feature Classification Code. MAF/TIGER stands for Master Address File/Topologically Integrated Geographic Encoding and Referencing, the census bureau's data base. S1400 is a neighborhood street.

FULLNAME: Name of feature (Hudson Correctional Facility is the "street name").

BBSPFLG: Block Boundary Suggestion Project Flag (for 2010). 4 = Hold as block boundary, 9 = do not hold.

CBBFLG: Census Bureau's intended block hold. 4 = hold, 9 = don't hold.

So comparing the two, you can identify features that the census bureau is deprecating.

BBSP_2020: This is my suggestion.  1 = hold, 2 = don't hold.

CHNG_TYPE: These are our suggested changes: DL = Delete Feature, CA Change attributes, AL = Add feature.  The Census Bureau would review the changes and decide whether to act on them.

JUSTIFY: Justification. This is free form text. The numbers were included as part of the text.

(4) The table windows stick around, so it is a good idea to delete them.

Looking at the whole map, with the prison roads selected, click on the Zoom to Select Icon (Magnifying Glass with Yellow). If you compare the satellite image to the mapped lines, you can see why I want to delete them.

Then click on the Zoom to Layer (magnifying glass with white box just to its right).

Then deselect features from all layers (Yellow Box with Red NO symbol). You can have features selected in multiple lines and it gets confusing.
72  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 28, 2016, 01:28:17 pm
Part 5



This image shows the icons that I use on a regular basis. There is no action, just some numbers around the edge to identify the icon.

(1) There is a current layer. Sometimes you will switch this, or it will get switched, and you will try to do something in QGIS and it won't respond. You will be looking at a line, and using the cursor to select it, and nothing happens. This is usually because there is a different layer selected.

You can uncheck a box, and a layer won't be displayed. Uncheck the box next to changes shapefile, and the red lines disappear. Uncheck the box next to Google Satellite, and the background disappears.
Check the boxes, and they return.

(2) You can Save a project. A project does not contain the data files (shapefiles, etc.) but rather a reference to them, and also includes current settings, including presentation parameters. It is a good idea to save a project every so often. You will be prompted before exiting QGIS, but not before you lose electrical power, or even an orderly shutdown.

I save all projects (.qgs) files in a common directory. This makes it easy to switch between projects, since QGIS remembers directories.

(3) You can open a different project. If you have made changes to your current project, you will be prompted to save it, before the project is opened.

(4) You can create a new (blank) project.

(5) Use the hand, to switch to panning. Click and hold, to drag the map around.

(6) Use the magnifying glass with a + to Zoom In. You can use use a marquee zoom (click on one corner of area to zoom to, and hold as you move the cursor to the other corner of the zoom area. Or click on a point, and it will double the scale while zooming about that point.

(7) Use the magnifying glass with a - to Zoom Out. The larger area you select, the slower the zoom out will be. Select a real tiny area and you will zoom out a lot. Or you can click on a point and the scale will be halved.

(8) Use the magnifying glass with a bit of yellow, to Zoom to Selection - QGIS uses yellow to highlight selections, so yellow in an icon indicates that it is related to a selection.

(9) Use the magnifying glass with a white square to Zoom to layer. Sooner or later you will get lost. Click on this to zoom to the full extent of a layer.

Zoom in on a particular area of the map.  Click on Zoom to Layer to return to full extent of the changes shapefile (ie Hudson)

(10) Use the magnifying glass with a "<" to back up to previous displayed extent.

(11) Use the yellow icon with the lasso for Graphical Selection (more on this later)

(12) Use the yellow icon with the script E for "expression" to select by expression.

(13) Use the yellow icon with the red NO symbol to deselect everything.

(14) Use the icon that looks like the Monopoly card for Connecticut, Vermont, or Oriental avenues to to Display The Attribute table.

(15) Use the icon that looks like a ruler to measure distances, areas, and angles.

At the bottom:

(16) Current location. The center of our projection is at 42.25 degrees N, 73.75 degrees W. The coordinates are distances (in meters) from that point.

(17) Current scale. You can also use this to set a particular scale, either typing in a number or using the pulldown menu.

(18) Rotate map. You can rotate vectors (lines), but not rasters (satellite image) so it is of somewhat less utility here.
73  General Politics / Political Geography & Demographics / Re: Hudson Block Boundary Suggestion Project (BBSP) on: May 28, 2016, 11:33:02 am
Directory of Prototype block files. Maine is state 23, Kennebec is county 11. The zip file is for the entire state, but I haven't found a shortcut to get county specific files.

1) Go to http://www.census.gov/rdo/ .
2) Under "Recent News", click on "2020 Census Program Phases"
You probably have been to this page, which has a lot of information about the BBSP and guides for using both their GUPS (the one you said was built over QGIS) and your own software.  But anyway, ...
3) Under "Phase 1 - Block Boundary Suggestion Project", under "Geographic Files", click on "Partnership Files" (note the "(use 2016 Partnership Files)" right after that hyperlink).
4) Select your preferred vintage (2015/V1 or 2016/V2 (I did what they said to and downloaded the the 2015 shapefiles for Maine, but only the statewide ones and those for Kennebec and Aroostook because of how big it all was; I had already downloaded the prototype block shapefiles for every Maine county).
5) Select your desired state and click "GO".
6) You can batch download up to five counties' shapefiles at a time.  For each batch download of 1-5 counties there will be a folder for both Maine and each county in that batch download.

The Prototype file is different than the Partnership files.
Oh, okay.  Is there data that the county specific prototype files (if they exist) might have that the state ones do not?  (That is the case for the partnership files)  Or is it just a matter of having to download more than you might need?  The prototype files, which I actually downloaded before I downloaded any partnership files, just seem to show block lines with no different lines for streets, city limits, etc. (there's only one shapefile (.shp) per county, just with four other "supporting files" for each .shp file; more supporting files resulted when I uploaded the shapefiles in ArcGIS explorer which I was using at the time, but there was still just one .shp file per county).

(I got rid of the false quote from a post of yours on May 24 that caused misattribution of quotes in our last couple posts - that was my bad).
I think that the prototype files may be intended for communication with the redistricting liaison, and thus cover all the counties of a state.

The partnership file has two census block files:

PVS_15_V2_tabblock2010_ssccc
PVS_15_V2_tabblock_ssccc

The first is the census block file from 2010. Since our target is the block boundaries for 2020, it is useful to know what was used in 2010.

In Hudson, I don't see any difference between the two partnership file. In places that have had new streets added, there might be new blocks, but I don't know for sure.

The prototype file is

bbsp_2015_block_ssccc

It reflects what the blocks would be based on current census planning. In effect it is saying, if you don't offer any suggestions, this is what we are going to do.

In Hudson, they have added a boundary around the prison to the edges file, which they intend to use as a block boundary. So that shows up as a new block. Unnamed streets appear to be downgraded, so that eliminates blocks, etc.

Incidentally, the "companion files" are also known as sidecar files. When you drag the .shp file into the map area (this movement is communicated by Windows between Windows Explorer and QGIS) QGIS knows to go get the sidecar files.

The .shp shapefile contains the actual coordinates of the points, edges, faces, etc.
The .dbf Dbase file contains the attributes of the edges (eg streetnames, etc.). You can open a dbf file, read-only in Excel.
The .prj file has the projection used for the points in the shapefile. It is a text file. The .prj file for all census files is the same, but QGIS doesn't know that a particular file is a "census file".
The .cpg file has the character set used for text. ASCII was historically used for computerized text. It is limited to the 26 upper case and lower case English letters. UTF-8 permits encoding of letters used in other languages. In the case of the US Census, this would be particularly to handle Spanish for Puerto Rico.
The .shx file is an index file for the shapefile. Because lines can have differing numbers of vertices, the .shp file has variable length records. This is efficient for storage, but inefficient for random access. The .shx file helps provide quicker access to the shapefile.


74  General Politics / Political Geography & Demographics / Re: Hudson QGIS on: May 28, 2016, 10:20:32 am
Part 4

We can change the display of a layer.



(1) Right Click on layer you want to change, and select Properties from the menu.
(2) Select Style
(3) Select Single Symbol
(4) Select Color. The menu allows you to select a standard color; compose a color; pick a color with an eyedropper, etc.
(5) Select width of color.
(6) Apply Changes.

Click on OK. If the color or width are not to your aesthetic tastes, change them. I thought the lines were a bit too wide, and the red a little too hot.

So under the color selection, I clicked on Choose Color, and then moved the vertical slider next to spectrum down a bit. I also reduced the width.
75  General Politics / Political Geography & Demographics / Re: Hudson Block Boundary Suggestion Project (BBSP) on: May 28, 2016, 03:18:44 am
Directory of Prototype block files. Maine is state 23, Kennebec is county 11. The zip file is for the entire state, but I haven't found a shortcut to get county specific files.

1) Go to http://www.census.gov/rdo/ .
2) Under "Recent News", click on "2020 Census Program Phases"
You probably have been to this page, which has a lot of information about the BBSP and guides for using both their GUPS (the one you said was built over QGIS) and your own software.  But anyway, ...
3) Under "Phase 1 - Block Boundary Suggestion Project", under "Geographic Files", click on "Partnership Files" (note the "(use 2016 Partnership Files)" right after that hyperlink).
4) Select your preferred vintage (2015/V1 or 2016/V2 (I did what they said to and downloaded the the 2015 shapefiles for Maine, but only the statewide ones and those for Kennebec and Aroostook because of how big it all was; I had already downloaded the prototype block shapefiles for every Maine county).
5) Select your desired state and click "GO".
6) You can batch download up to five counties' shapefiles at a time.  For each batch download of 1-5 counties there will be a folder for both Maine and each county in that batch download.

The Prototype file is different than the Partnership files.
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