Local vs regional road connections

[muon2]

Erosity is erosty and chops are chops. Two different things. If a using a local county road connection avoids a locality chop, I would like to be able to use it as an option. Having more map options rather than fewer is good thing, not a bad thing.

Regarding traveling chops, rather than just ban them, I think it might be wise to consider allowing them, but if two maps have the same chop count, then the map that avoids traveling chops would be preferred, as superior from a chop standpoint. Again that provides flexibility. My little chop that caused a traveling chop in NC I did not consider a policy problem. So it should be an option, assuming there was no other map with the same chop count that avoided such a traveling chop. And indeed to avoid it, I had to create an extra chop. Minimizing chops should be encouraged, not discouraged.

One query for clarification. I thought we defined traveling chops as those beasts that split two counties between the same two districts. At least that was their meaning when we did the MI exercise. I've used bridge chops to refer to fragments that connect whole counties.

My feeling with both bridge chops and local connections is that since they are used to avoid chops or cluster penalties (which accrue as chops), then if they are permitted they too should come with chop penalties.

[jimrtex]

Are you now ok with the CA county connections that I mentioned? As I said the rule arose in discussion about mountains out west, where such connections were not seen as good policy. The rule was tested in Midwestern states (MI in particular) with counties that had minimal overlaps of boundaries, no highway connections, but nonetheless had local roads.

California did not consistently apply the rule about coming into San Benito County via a road that sneaks into Santa Clara County. It appears that those who advocated for the separation were doing so for political expediency.

[Torie]

Erosity is erosty and chops are chops. Two different things. If a using a local county road connection avoids a locality chop, I would like to be able to use it as an option. Having more map options rather than fewer is good thing, not a bad thing.

Regarding traveling chops, rather than just ban them, I think it might be wise to consider allowing them, but if two maps have the same chop count, then the map that avoids traveling chops would be preferred, as superior from a chop standpoint. Again that provides flexibility. My little chop that caused a traveling chop in NC I did not consider a policy problem. So it should be an option, assuming there was no other map with the same chop count that avoided such a traveling chop. And indeed to avoid it, I had to create an extra chop. Minimizing chops should be encouraged, not discouraged.

One query for clarification. I thought we defined traveling chops as those beasts that split two counties between the same two districts. At least that was their meaning when we did the MI exercise. I've used bridge chops to refer to fragments that connect whole counties.

My feeling with both bridge chops and local connections is that since they are used to avoid chops or cluster penalties (which accrue as chops), then if they are permitted they too should come with chop penalties.

I meant bridge chops. Although those are a bit hard to define. Does any chop need to be from a whole county, unless the CD has no whole counties? Or if two fragment counties, does one of the fragments need to be filled in first before chopping elsewhere?  

On your comment about penalties, I really think that if you say, hey, if a bridge chop reduces the chop count below a map without such a bridge chop, then that map wins, and otherwise it loses unless it say reduces an erosity penalty, and then the two maps are tied on chops, and you then compare erosity scores.

Oh, on this road cut thing, it should be quite easy to program come to think of it. You just program in:

1. All CD's must be contiguous, and to be contiguous, they must  be connected within by a land mass that is more than a mere corner, and between counties therein, such counties must be connected by (a) a county, state or federal numbered highway, or b) if divided by water, a bridge or an all season ferry which carries vehicles.

2.Unless otherwise in a county that is wholly within one CD, a land mass that is not connected by a paved road that has a number from a county, state or federal entity, is not deemed contiguous.

3. Adjacent counties that are in separate CD's shall incur one erosty point if connected by a state or federal numbered highway.

That seems to do it, doesn't it?

[muon2]

The addition of county roads may work - with some caveats. A cursory check shows there is far less consistency with what a county road means than what a state road means. Not every state numbers their county roads, some use just letter and some use a letter followed by a number. Some counties have roads that are numbered, but not in the sense I think you mean (eg 12 mile road in Kent county MI). Some states have multiple tiers of county roads (MI has three tiers). Some states relegate township roads to a lower class than county roads, but that obviously doesn't happen in states without townships. The problem is that the lowest unit of government gets stuck maintaining all unincorporated public roads, so which are "numbered".

You're from CA, does it make sense for Fresno to connect to San Benito? It would with county road J-1.

Here's my original definition of connection with your proposed change underlined. I haven't tried to define county road yet, but that would need to be part of this.

A political unit can be represented by a node that is the political center of that unit. For a county the node is the county office where the elected officials meet. For a city or town the node is the city or town hall. For a precinct the node is the polling place. Units are connected based on the path that connects their nodes.

Two units are locally connected if there is a continuous path of public roads that allow one to travel between the two nodes without entering any other unit. Local connections can include seasonal public roads. A local connection path can be traced over water without a bridge if there is a publicly available ferry that provides part of the connection. Units smaller than a county must be locally connected within a district.

Two counties are regionally connected if there is a continuous path of numbered county, state or federal highways that allow one to travel between two nodes without entering any other county. If a node is not on a numbered highway, then the connection is measured from the point of the nearest numbered highway to the node. The path may only use roads that are generally available all year. Regularly scheduled year-round ferry service may be included in the path of a regional connection. Counties must be regionally connected to be connected, except that counties within a cluster are connected if they are locally connected.

There is often more than one possible path to connect to nodes. For both local and regional connections the connection between two units is considered to be based on the path that takes the shortest time as determined by generally available mapping software.

[jimrtex]

And yes I know about US 52 cutting a corner of Cabarrus. The metric is whether you can go between two county seats on state highways without going into a third county. It is easy to apply. The moment the door is opened to allow a road to go a little bit into another county the metric becomes exceedingly messy as one tries to define how much goes beyond a little.

The rule lacks in common sense.

When I spoke in 2010 with redistricting experts who had mapped states in previous cycles they said that one of the easiest ways to gerrymander is to grab populations across a river or forest that you couldn't otherwise conveniently reach, but were contiguous. One even suggested that if he was to only propose only one change to reduce gerrymandering it would be that it had to be possible to reach all parts of a district by car without leaving the district. That sounds like common sense to me.

If you were to put Rowan and Stanley in the same district, you would not be crossing a river or forest. You would be nicking the corner of Cabarrus County.

Do you think that county officials in Rowan and Stanley never work together because Cabarrus County is "between" them? If their were an auto accident on US 52, who could get there fastest - someone from the Rowan or Stanley sheriff's office, or someone from Cabarrus County?

While one person suggested that you must be able to drive to all parts of a district, he probably had done a superficial analysis of what that literally means.

[Torie]

The local road culture may need to be state specific as to nomenclature. The main thing is publically maintained two lane pavement. If Fresno to San Benito has such a road, than I don't have a problem with it. You still have an incentive to chop there from an erosity standpoint. But using such roads to avoid county chops I think makes it all worthwhile.

[muon2]

The local road culture may need to be state specific as to nomenclature. The main thing is publically maintained two lane pavement. If Fresno to San Benito has such a road, than I don't have a problem with it. You still have an incentive to chop there from an erosity standpoint. But using such roads to avoid county chops I think makes it all worthwhile.

There's a substantial difference between publically maintained roads and "numbered" county roads. I'm not willing to go so far as to include all pubic roads - I've run across subdivision roads that allow one to take a winding path through a residential neighborhood to cross between counties, and I don't think that should count as a regional connection. I also don't want to have to discern which farm roads are paved. As I noted there are numbered state highways in western states that are not paved, and I'm ok with those, since they usually are the main transportation link in their area.

What I'm interested in is a clear definition of county road that doesn't include every local unincorporated road, but is broad enough to cover most states. I don't mind a couple of exceptions, but I don't think that 50 separate definitions is consistent with my generic model. Then I can test it to see how it affects erosity computations. I'm most concerned about the impact on marochopped counties. We went through a lot of effort in Kent county MI to come up wit a model of connections that balanced rural and urban erosities, then we applied it in the Detroit area in a way that made sense. That rural-urban balance is a critical element to the whole concept of erosity.

[Torie]

I largely agree with what you say. However, if a state does not have numbered county highways, an accommodation will need to be made that is reasonable.

With respect to macro-chopped counties, job one is to avoid locality chops, because that causes the erosity score to collapse, along with generating a full bore chop for each locality chopped - an utter scoring disaster. So given that, there really isn't much, if any, room to play partisan games. And the rules should be flexible enough to facilitate avoiding such chops. I consider avoiding locality chops to be critically important, and I suspect county election boards will agree with me. And within counties, any paved road will do, no? It is only when crossing into a county, that we have this special metric about what paved roads are allowed to be used.

[muon2]

When we were engaged in the MI effort we looked specifically at a number of alternate scoring methods for the Kent chop. It was heavily informed by the notion that the local subcounty units not be chopped.  To measure erosity I used local road connections, only state highways, and a hybrid of the two. You and the others supplying Mi maps provided your sense of how the plans should score relative to each other, and then I compared that with my specific scoring method. The result that best matched what the eye desired was a hybrid of local connections within a county and state highway connections between counties. An all local approach like you want in NC was one of the models considered, and the scoring result did not match well with your estimation, or anyone else's, of what appropriate scores should be.

The meaning of locality chops is not clear in a state like NC. There are no statutory electoral units between the county and the precinct, in contrast to states like MI. Electoral divisions in NC and other southern and western states do not generally follow localities for that reason. We can look at the place lines on DRA, but they clearly don't matter to the election authorities when it comes to ballot types. For the VA exercise I generally had to look at other data to get a sense of CoIs that should make up the county subunits.

As I continue to review that status of county roads, I see far less consistencies than I hoped for (and I wasn't expecting much). At this point I'm prone to leave them out of the general rule. I provide for users of the system to amend rules to fit specific state needs, and I think that whether state roads should extend to certain numbered county highways would be a matter for the group using the rules. As I noted in the first paragraph, I would not recommend using local roads for all connections since I can show what that does to the erosity scores from our MI exercise.

[Torie]

Remind me again of what disaster befell Kent by not requiring state highway connectivity between counties? Perhaps you could repost the map. You just said local road connectivity was OK within a county. So I don't see how the issue can be erosity within a county. Nor do I see how allowing county road connectivity between counties makes the map uglier to the eye per se. In any event, there is an incentive for cuts between counties to be where there are no state highways, since that improves the erosity score.

Of course, it's up to a state to do what it wants. It could allow local highway connections or not, defined as it so chooses, but if it does not allow such local connections, that may well cause more chops as the price. It just seems arbitrary to me. I suspect most legislators would agree, unless allow the Kent example, you can make a good case for it. And unfortunately, I just don't recall the exact details now of that example, to apply again in this context.

For counties with no subunits, how do you assess the score for the chop (other than the erosity score for state highway cuts, with which I agree)?

[muon2]

Remind me again of what disaster befell Kent by not requiring state highway connectivity between counties? Perhaps you could repost the map. You just said local road connectivity was OK within a county. So I don't see how the issue can be erosity within a county. Nor do I see how allowing county road connectivity between counties makes the map uglier to the eye per se. In any event, there is an incentive for cuts between counties to be where there are no state highways, since that improves the erosity score.

Of course, it's up to a state to do what it wants. It could allow local highway connections or not, defined as it so chooses, but if it does not allow such local connections, that may well cause more chops as the price. It just seems arbitrary to me. I suspect most legislators would agree, unless allow the Kent example, you can make a good case for it. And unfortunately, I just don't recall the exact details now of that example, to apply again in this context.

For counties with no subunits, you assess the score for the chop in how (other than the erosity score for state highway cuts, with which I agree)?

Perhaps if time permits one of us can search for the thread. It's not a single map, but a set of maps from the proposals put forth by train, jimrtex, you and I. The Kent chop was a common feature in many and simple enough to analyze for erosity in a way that the Detroit area was not.

We independently ranked the set of submitted maps on how we thought they should turn out for erosity. Then I calculated scores using different definitions of connections. The definition that best matched our preconceived expectations was the one that we adopted for the rest of the MI enterprise. That model generated no controversy when applied to the Detroit area and to more rural stretches. There were even maps at that time that went back due to lack of a regional connection, and I did not detect any complaints. I assumed this was because we thought the issue settled after we all put a lot of time in selecting the right balance between regional and local concerns.

[Torie]

Remind me again of what disaster befell Kent by not requiring state highway connectivity between counties? Perhaps you could repost the map. You just said local road connectivity was OK within a county. So I don't see how the issue can be erosity within a county. Nor do I see how allowing county road connectivity between counties makes the map uglier to the eye per se. In any event, there is an incentive for cuts between counties to be where there are no state highways, since that improves the erosity score.

Of course, it's up to a state to do what it wants. It could allow local highway connections or not, defined as it so chooses, but if it does not allow such local connections, that may well cause more chops as the price. It just seems arbitrary to me. I suspect most legislators would agree, unless allow the Kent example, you can make a good case for it. And unfortunately, I just don't recall the exact details now of that example, to apply again in this context.

For counties with no subunits, you assess the score for the chop in how (other than the erosity score for state highway cuts, with which I agree)?

Perhaps if time permits one of us can search for the thread. It's not a single map, but a set of maps from the proposals put forth by train, jimrtex, you and I. The Kent chop was a common feature in many and simple enough to analyze for erosity in a way that the Detroit area was not.

We independently ranked the set of submitted maps on how we thought they should turn out for erosity. Then I calculated scores using different definitions of connections. The definition that best matched our preconceived expectations was the one that we adopted for the rest of the MI enterprise. That model generated no controversy when applied to the Detroit area and to more rural stretches. There were even maps at that time that went back due to lack of a regional connection, and I did not detect any complaints. I assumed this was because we thought the issue settled after we all put a lot of time in selecting the right balance between regional and local concerns.

Nothing is ever fully settled for the lawyer class. If it were, we would have nothing to do.

[muon2]

Remind me again of what disaster befell Kent by not requiring state highway connectivity between counties? Perhaps you could repost the map. You just said local road connectivity was OK within a county. So I don't see how the issue can be erosity within a county. Nor do I see how allowing county road connectivity between counties makes the map uglier to the eye per se. In any event, there is an incentive for cuts between counties to be where there are no state highways, since that improves the erosity score.

Of course, it's up to a state to do what it wants. It could allow local highway connections or not, defined as it so chooses, but if it does not allow such local connections, that may well cause more chops as the price. It just seems arbitrary to me. I suspect most legislators would agree, unless allow the Kent example, you can make a good case for it. And unfortunately, I just don't recall the exact details now of that example, to apply again in this context.

For counties with no subunits, you assess the score for the chop in how (other than the erosity score for state highway cuts, with which I agree)?

Perhaps if time permits one of us can search for the thread. It's not a single map, but a set of maps from the proposals put forth by train, jimrtex, you and I. The Kent chop was a common feature in many and simple enough to analyze for erosity in a way that the Detroit area was not.

We independently ranked the set of submitted maps on how we thought they should turn out for erosity. Then I calculated scores using different definitions of connections. The definition that best matched our preconceived expectations was the one that we adopted for the rest of the MI enterprise. That model generated no controversy when applied to the Detroit area and to more rural stretches. There were even maps at that time that went back due to lack of a regional connection, and I did not detect any complaints. I assumed this was because we thought the issue settled after we all put a lot of time in selecting the right balance between regional and local concerns.

Nothing is ever fully settled for the lawyer class. If it were, we would have nothing to do.

But the bane of model testing for a scientist is shifting the test conditions before a full test is complete. It results in data sets that aren't fit to publish.

[Torie]

I'm giving your model a road test as it were. You should thank me, rather than be annoyed.

[muon2]

I'm giving your model a road test as it were. You should thank me, rather than be annoyed.

Great then we should see how well it performs under the current rules. If it fails to produce a reasonable map in multiple occasions, then it should be modified. One outlier isn't convincing.

[jimrtex]

This is a network representation of North Carolina counties superimposed over an outline map of the state.



The nodes (blue circles) represent the counties, including the boundaries, population, etc. The position of the node over the map doesn't provide any information. I've used the internal points of the counties calculated by the census bureau.

The links represent the contiguity relationship between counties. Two county nodes are linked if the counties they represent are contiguous.

The red squares represent point contiguity, which we are not permitting. If we did, then links would cross. This would not make the network invalid, though it would make it non-planar. We don't permit use of point contiguity for policy reasons. Districts that cross each other are decidedly non-compact, and are little better than non-contiguous districts.

In building a district from whole counties, we can imagine snipping the links between counties in different districts. Rather than snipping the center of the link, and leaving the remnants dangling, we completely remove the link.

Alternatively, we can build a district by traveling along the links collecting counties and population as we go.

The more links we snip, the less compact our district will tend to be. I suspect it is possible to create a district from the western tip, northeast along the Tennessee boundary, across the state along Virginia, and then down the coast to Wilmington. We would snip a large number of links, or alternatively retain very few as we create a string of 30 counties.

The concept of connected counties is that some counties have a stronger relationship than mere contiguity. It is a COI concept, suggesting that they are neighbors, rather than merely contiguous. The central idea is that you can easily travel between the counties. The roads were created because there was a need to travel between counties, the existence of roads then reinforces the relationship between the counties.

In some cases it is difficult to travel between adjacent counties. There might be water or mountain barriers. The contiguity might be limited and no easy way to travel between the counties.

We can demonstrate the concept with states. Kentucky and Missouri are contiguous, as are New York and Rhode Island, and Minnesota and Michigan. It is not easy to travel between the pairs of states and would likely require a boat.

If we were traveling between New York City and Providence, Louisville and St.Louis, or Detroit and Minneapolis, we would almost assuredly not travel directly from one state to the other.

Traveling from New York City to Providence we would travel the length of Connecticut. From Albany we would likely travel across most of Massachusetts. New York and Rhode Island are not connected.

Driving from Detroit to Minneapolis, we would likely drive through Chicago. We could use the ferry across Lake Michigan, but not in winter, and we would still have to cross Wisconsin. We could travel through the Upper Peninsula and drive quickly through Superior, but the route is circuitous. Michigan and Minnesota are not connected.

You can drive from Louisville to St. Louis in a direct route. If you drive across the southern tips of Indiana and Illinois you avoid most of the people. And you can take a somewhat longer route across Kentucky and then drive into Missouri.

But this route requires a crossing into Illinois south of Cairo. Even though less than a mile is within Illinois, Muon2 would argue that the two states are not connected. I believe that they are.

On the network, the links between counties that are clearly connected are in blue. Those that there are contiguous but possibly not connected are in yellow. Muon2 and I likely agree that some are not connected, and perhaps that some are connected.

[Torie]

I'm giving your model a road test as it were. You should thank me, rather than be annoyed.

Great then we should see how well it performs under the current rules. If it fails to produce a reasonable map in multiple occasions, then it should be modified. One outlier isn't convincing.

Well I have already pointed out some of the downsides based on actual mapping experience. I guess in the end, states if they have any interest in your approach, will make up their own minds. I still think that using the blue roads for erosity testing, and allowing the yellow roads per jimrtex's NC map, for CD's to make use of, is a reasonable and sensible compromise. I would still like to see what you were talking about with Kent. I thought that was about internal connections, not cross county connections.

[muon2]

Well said jimrtex, especially the CoI explanation. BTW you need a connection from Washington to Bertie.

Our differing views stem from my strong propensity to avoid paths that cross outside the district. In this case that means paths that go outside the two counties considered for a connection. I think Torie favors this path containment as well, but wouldn't impose the CoI standard of a state highway.

I think that makes four categories of links.

1) Contiguous: the areas share a border greater than a single point.
2) Locally connected: contiguous areas where public roads provide a link without passing through an intervening county.
3) Nearly connected: contiguous areas where there is a convenient state highway linking them, but the path may briefly pass through intervening counties.
4) Regionally connected: contiguous areas where state highways provide a link without passing through an intervening county.

I view the approach as building a region of a whole number of districts by following connections. Then separating regions of more than one district using a minimum number of chops. The FL Senate exercise was a case in point.

Chops modify the connection network.

Chops less than a specified size (5% for CDs) split a single node into two connected nodes. The existing connections are assigned to the respective nodes based on where the primary path associated with the connection crosses the border.

If all chops are treated as above, districts in populous urban areas come out with artificially low erosities regardless of their shape. Chops in these areas need a denser network to assess district shapes and maintain parity with large multicounty rural districts.

So, chops in excess of the specified size are macrochops. Macrochops split the county into a network of nodes based on agreed subunits. Connections are made between these new subunits and from subunits to adjacent counties. Based on the Kent exercise, subunits use local connections within a county and regional connections to adjacent counties. The limitation of cross-county connections to regional links for subunits was an important result from the work in MI to maintain the rural-urban balance for erosity.

[Torie]

"and regional connections to adjacent counties."

For purposes of what exactly? Counting chopped roads? As a requirement for the path into the chopped county?  Or both?  If a Kent chop is a mess visually, won't it cut a poor erosity score as it cuts local roads? I would really like to see an example of how allowing local roads for entry and for allowing their use for two counties to be in one CD, creates a bad map, that makes it worthwhile to go for an alternative map with more chop related penalty points.

[jimrtex]

You must be logged in to read this quote.

Fixed.

Well said jimrtex, especially the CoI explanation.

Our differing views stem from my strong propensity to avoid paths that cross outside the district. In this case that means paths that go outside the two counties considered for a connection. I think Torie favors this path containment as well, but wouldn't impose the CoI standard of a state highway.

I think that makes four categories of links.

1) Contiguous: the areas share a border greater than a single point.
2) Locally connected: contiguous areas where public roads provide a link without passing through an intervening county.
3) Nearly connected: contiguous areas where there is a convenient state highway linking them, but the path may briefly pass through intervening counties.
4) Regionally connected: contiguous areas where state highways provide a link without passing through an intervening county.

I view the approach as building a region of a whole number of districts by following connections. Then separating regions of more than one district using a minimum number of chops. The FL Senate exercise was a case in point.

My viewpoint is that each node represents a sub-network of areas within the county. We collapse the subnetworks into a single point for simplification, and to strongly stress the use of whole counties. We only need to examine these subnetworks, if we are forced into splitting counties.

In Florida, I approached it as a matter of decomposing the statewide problem into smaller more manageable problems. After dividing the map into apportionment regions, the division into individual districts can be handled independently. In Florida, there could be redistricting commissions for each county, that would delineate commissioner districts, and possibly city council districts. If necessary, they would participate in the division of their counties into districts.

In Florida, there were a couple of different ways that the regions could be arranged. At that point, the process could be forked, and then the decision on the statewide map could be based on which produced better districts in the alternative regions.

Chops modify the connection network.

Chops less than a specified size (5% for CDs) split a single node into two connected nodes. The existing connections are assigned to the respective nodes based on where the primary path associated with the connection crosses the border.

If all chops are treated as above, districts in populous urban areas come out with artificially low erosities regardless of their shape. Chops in these areas need a denser network to assess district shapes and maintain parity with large multicounty rural districts.

So, chops in excess of the specified size are macrochops. Macrochops split the county into a network of nodes based on agreed subunits. Connections are made between these new subunits and from subunits to adjacent counties. Based on the Kent exercise, subunits use local connections within a county and regional connections to adjacent counties. The limitation of cross-county connections to regional links for subunits was an important result from the work in MI to maintain the rural-urban balance for erosity.

If a wider deviation range is permitted, you can do away with some chops. Chops needed to equalize between regions can be treated as independent problems. Chops within multidistrict regions are not chops at all. Respect for counties is a constraint on the division of townships, cities, and other subcounty areas.

[muon2]

I've been doing some research on the NC road system. They claim to have the greatest number of road miles in the US. That's in large part because there are no county roads in NC. Any road not maintained by a municipality is maintained by the state. Most of those roads are called secondary roads (SR) and some have numbers used for DOT purposes, but they aren't always marked and they aren't intended for navigation. They move them up to primary state roads when they are of regional significance.

For instance the roads Torie initially posted on the Montgomery-Davidson border are SR's. Mapquest doesn't show those numbers at all and Bing maps only show a number on the Montgomery side (Blaine Rd  NC - 1161) but not on the Davidson side (Badin Lake Rd). Based on the NCDOT guidance I would classify them as local roads rather than numbered highways.

OTOH, there are lots of legitimate numbered state highways that aren't "highways". I'm going through all the yellow links on jimrtex's map to see how I would classify them. I'll post that soon.

[Torie]

"OTOH, there are lots of legitimate numbered state highways that aren't "highways"." 

What does that mean?

[muon2]

"OTOH, there are lots of legitimate numbered state highways that aren't "highways"." 

What does that mean?

It means they didn't show up on jimrtex's map as blue links, but I would include them.



In this map I have revisited the yellow links on jimrtex's map.

Blue are regional connections based on continuous state highways between two county seats that don't enter a third county. The dark blue links were those not identified previously, but meet my criteria.

Green is a all year ferry connection that meets the criteria for a regional connection.

Yellow are local connections that rely on local roads to establish a path between counties.

Orange are near connections based on state highways where the highway path cuts a short distance through a third county, such as at a corner.

Gold are connections equivalent to both yellow and orange.

Pink are contiguous counties without a connection.

Red squares are places with point contiguity.

[jimrtex]

I'm giving your model a road test as it were. You should thank me, rather than be annoyed.

Great then we should see how well it performs under the current rules. If it fails to produce a reasonable map in multiple occasions, then it should be modified. One outlier isn't convincing.

Well I have already pointed out some of the downsides based on actual mapping experience. I guess in the end, states if they have any interest in your approach, will make up their own minds. I still think that using the blue roads for erosity testing, and allowing the yellow roads per jimrtex's NC map, for CD's to make use of, is a reasonable and sensible compromise. I would still like to see what you were talking about with Kent. I thought that was about internal connections, not cross county connections.

You misunderstand my map.

The links are not roads. They are a graphical representation of a relationship between counties, that of contiguity. The network is superimposed over the map to illustrate the derivation of the map.

The links can have attributes associated with them. For example, they could have the length of the border between the two counties. Certainly, they could indicate whether the two counties are "neighbors" or merely adjacent.

Some of the yellow links could become red links, indicating they are not neighbors, even though they are adjacent. Others could become green, indicating they are neighbors.

The blue links would all become green links. The blue links are those that are trivially obvious. It is easy to travel directly between the counties, using numbered highways.

Muon2 and I would disagree on the further classification of some of the yellow links, but would likely agree on others.

The census bureau has a county adjacency file for the entire country, which shows the contiguous counties for each county.

I extracted the North Carolina portion; and removed the interstate adjacent counties (to Virginia, Tennessee, Georgia, and South Carolina). The census bureau classifies each  county as being adjacent to itself, so the self-adjacent were eliminated. And the census bureau lists counties adjacent to each county, so that Kings (NY) is adjacent to Queens (NY), and Queens (NY) is adjacent to Kings (NY). I removed the second copy of these duplicate links.

This left 256 adjacent pairs of counties. Another 12 were eliminate due to point contiguity. For example, Guilford and Stokes are adjacent as are Forsyth and Rockingham. This could be automated. I did it with a spreadsheet, though I manually entered formulas, and stepped through the process.

It might be possible to automate further classification of the links, but I did it by hand. It can certainly be assisted by computers. It could also be farmed out to the counties. If two counties agreed, it would probably be accepted by the state.

I would not permit use of red links for building districts. I probably would use them for measuring erosity. Generally, they correspond to fairly short boundaries, so that there is little penalty.

[Torie]

"Muon2 and I would disagree on the further classification of some of the yellow links, but would likely agree on others."

What do you think your metric is, as compared to his?