Future electoral votes?

[muon2]

PR would probobly be about three votes.

I would say 6 or 7

The 2000 census for PR was 3,809 thousand, and the average CD had a population of 648 thousand. The 2000 census would almost certainly be the basis for any new state before 2008, so if PR became a state it would have 6 Representatives. If the US Virgin Islands were added to PR, the extra 109 thousand would not change the initial apportionment.

[muon2]

2012-2020

I took the 2000 census and the 2003 update from the census. If I project the growth between 2000 and 2003 to April 1, 2010 I get the following changes to Congressional apportionment.

AL -1 (8 EV)
AZ +1 (11 EV)
CA +2 (57 EV)
FL +2 (29 EV)
GA +1 (16 EV)
IL -1 (20 EV)
IA -1 (6 EV)
LA -1 (8 EV)
MA -1 (11 EV)
MO -1 (10 EV)
NV +1 (6 EV)
NY -2 (29 EV)
OH -2 (18 EV)
PA -1 (20 EV)
TX +3 (38 EV)
UT +1 (6 EV)

[muon2]

I took the 2000 census and the 2003 update from the census. If I project the growth between 2000 and 2003 to April 1, 2010 I get the following changes to Congressional apportionment.

AL -1 (8 EV)
AZ +1 (11 EV)
CA +2 (57 EV)
FL +2 (29 EV)
GA +1 (16 EV)
IL -1 (20 EV)
IA -1 (6 EV)
LA -1 (8 EV)
MA -1 (11 EV)
MO -1 (10 EV)
NV +1 (6 EV)
NY -2 (29 EV)
OH -2 (18 EV)
PA -1 (20 EV)
TX +3 (38 EV)
UT +1 (6 EV)

I agree, except that New York would narrowly keep their 28th congressman ahead of California's 55th.

Also, Alabama could keep its 7th, and Minnesota could lose its 8th with a narrow shift.  These latter two are interesting, because Minnesota will have about a CD's worth greater population, but could end up with the same, one more or two more representatives.

The last few seats I apportioned were:
432 - CA 55
433 - PA 18
434 - MN 8
435 - MI 15

The next in line were
NY 28
IL 19
AL 7

Then after a gap
CA 56
MD 9
OH 17
TX 36

It's pretty easy to move any of the last four out and the next three in. Before year's end, I expect the Census Bureau to release the July 1, 2004 estimates. I'll rework my projections at that point.

[muon2]

Based upon Census estimates for 2010, this is how many reps each state would have after reapportionment. Add 2 to each for the EV. These are based upon the formula actually used for reapportionment.

AK   1
AL   7
AZ   8
AR   4
CA   58
CO   7
CT   5
DE   1
DC   0
FL   26
GA   13
HI   2
ID   2
IL   18
IN   9
IA   4
KS   4
KY   6
LA   7
ME   2
MD   8
MA   9
MI   14
MN   7
MS   4
MO   9
MT   2
NE   3
NV   3
NH   2
NJ   13
NM   3
NY   27
NC   13
ND   1
OH   16
OK   5
OR   6
PA   18
RI   2
SC   6
SD   1
TN   9
TX   34
UT   4
VT   1
VA   11
WA   10
WV   3
WI   8
WY   1
TTL   435

what Michigan is going to lose another seat in 2010. 

As i mentioned earlier, MI is sitting on the bubble for 2010. Using the 2003 census estimates and projecting it forward to 2010, put MI as the 435th seat to given out. It would take very little change to move them to seat number 436, meaning that they lose one seat.

I've seen the Census projections for 2010 that Bogart uses. I'm not convinced of the model, since it was largely set by patterns in the 1990's. I've used the 2003 estimates which should reflect new demographic patterns since 2000. For instance, recent estimates greatly reduce the rate of growth in CA. The older projections have 2-4 more house seats for CA than do projections based on the new estimates.

[muon2]

I agree, except that New York would narrowly keep their 28th congressman ahead of California's 55th.

Also, Alabama could keep its 7th, and Minnesota could lose its 8th with a narrow shift.  These latter two are interesting, because Minnesota will have about a CD's worth greater population, but could end up with the same, one more or two more representatives.

The last few seats I apportioned were:
432 - CA 55
433 - PA 18
434 - MN 8
435 - MI 15

The next in line were
NY 28
IL 19
AL 7

Then after a gap
CA 56
MD 9
OH 17
TX 36

It's pretty easy to move any of the last four out and the next three in. Before year's end, I expect the Census Bureau to release the July 1, 2004 estimates. I'll rework my projections at that point.

How did you project the 2010 population?

I used   

   p2010 = c2000 + (e2003 - c2000) * (10/3.25)

The census estimates are for July 1st, the census for April 1st, so there is 3.25 years between the census and the 2003 estimate.  If you use 3 instead of 3.25, it will increase the projected increase by 8.3%.  For California, this would amount to about 1% more people.

Your formula assumes a linear increase. I assume that the percentage increase is compounded like interest. I first find the annual rate of increase using

rate = (e2003/c2000)^(1/3.25) - 1

Then I find the projection to 2010 using

e2010 = c2000 * (rate + 1)^10

Financial functions in spreadsheets take care of both these functions directly.