The final 2010 census figures (giving the United States a 2010 population overall of 308.7 million people) have shifted eleven seats in Congress from the Northeast and Midwest to the Mountain West and the South. All nine states in the Northeast and Midwest whose allotment of Congressional seats changed saw that allotment decline. In the West and South, eight states increased the size of their Congressional delegations, while Louisiana, in the aftermath of Hurricane Katrina, lost one seat in Congress. Colorado's Congressional delegation, as expected, stayed constant at seven seats in the House of Representatives.
The shift relative to the 2000 apportionment favors Republicans in both the House of Representatives and the electoral college used to elect the President.
Of the states that will get greater representation in the 2012 election, five states that gains eight seats in Congress are red states that voted for McCain in 2008 and Bush in 2004, two states that gained three seats in Congress voted for Obama in 2008 but Bush in 2004, and one state that gained one seat in Congress is a blue state that voted for Obama in 2008 and Kerry in 2004.
Of the states that will lose seats in Congress in the 2012 election, six states that lost seven seats in Congress are blue states that voted for Obama in 2008 and Kerry in 2004, two states that lost three seat in Congress voted for Obama in 2008 but Bush in 2004, and two states that lost two seats in Congress are red states that voted for McCain in 2008 and Bush in 2004.
Thus, red states have gained a net six seats in Congress, blue states have lost a net six seats in Congress, and states that voted for Obama in 2008 and Bush in 2004 have the same number of net seats in Congress.
While the strong growth of Democratic party leaning demographic groups like minorities and younger voters, and the increasing secularization of the American public tends to favor the Democrats, the low levels of voter registration and diffuse nature of the growing demographics that favor Democrats growth have prevented the intra-electorate trends from being important as the geographic shifts in population in influencing the balance of political power in the United States.
Long Term Trends
The shift continues and reflects trends over the last forty years largely associated with a shift of the American economy from an industrial one to a post-industrial one (a bland description that reflect the fact that even the best informed observers lack a simple heuristic explanation of what our economy is based upon these days), and secondarily a shift from rural areas to urban ones.
Since 1970, states have gained or lost representatives in Congress as follows (with the parenthetical number indicating the number of Congressional seats in the 2012 election):
Texas +12 (36)
Florida +12 (27)
Georgia +4 (14)
North Carolina +2 (13)
South Carolina +1 (7)
Tennessee +1 (9)
Virginia +1 (11)
No change: Maryland (8), Alabama (7), Arkansas (4), Delaware (1)
Kentucky -1 (6)
Oklahoma -1 (5)
Mississippi -1 (4)
West Virginia -1 (3)
Louisiana -2 (6)
Mountain West and Pacific (+26)
California +10 (53)
Arizona +5 (9)
Nevada +3 (4)
Washington +3 (10)
Utah +2 (4)
Colorado +2 (7)
New Mexico +1 (3)
Oregon +1 (5)
No change: Hawaii (2), Idaho (2), Alaska (1), Wyoming (1)
Montana -1 (1)
Midwest and Great Plains (-27)
Ohio -7 (16)
Illinois -6 (18)
Michigan -5 (14)
Iowa -2 (4)
Missouri -2 (8)
Indiana -2 (9)
South Dakota -1 (1)
Kansas -1 (4)
Wisconsin -1 (8)
No change: Minnesota (8), Nebraska (3), North Dakota (1)
New York -12 (27)
Pennsylvania -7 (18)
Massachusetts -3 (9)
New Jersey -3 (12)
Connecticut -1 (5)
No change: Maine (2), New Hampshire (2), Rhode Island (2), Vermont (1)
Reapportionment's Interaction With Realignment
The shift of political power to the South and Mountain West has coincided with a period in which conservative Democrats in Congress, mostly in the South, have been replaced by Republicans, and moderate Republicans in Congress, mostly in the Northeast and Pacific States, have been replaced by Democrats in Congress.
In the Republican party, the trends reinforce each other, by shifting the central of gravity of the Republican party further towards white Southern Evangelical Christians and Mormons. The electoral importance of "Reagan Democrat" blue collar union members and farmers to the Republican coalition has been reduced, and fossil fuel extraction interests have taken at least as many hits as they have made gains.
The realignment together with demographic trends tend to favor a shift to the right in the Republican party on social issues, but may undermine the strength of big money financial interests, the so called Rockefeller Republicans who live in coastal areas where Democrats are dominant in politics and a cosmopolitan identity is necessary to do business, in the Republican party. It may also undermine the ability of Republicans to draw support in any part of the mainstream entertainment industry that provided it with notable leaders like Ronald Reagan and Arnold Schwarzenegger. There will be pressure for economic conservatives outside socially conservative Republican strongholds and young conservatives to dissociate themselves from the Republican party's red state strongholds if they have any desire to remain relevant in state and local politics, a tendency that the electoral success of the Tea Party movement which publicly focused on economic rather than social issues, despite having a very culturally conservative composition, may encourage.
In the Democratic party, the demographic trends weaken the importance of blue collar private sector labor unions in the coalition, while increasing the relative importance of ethnic minorities including Hispanics, African Americans, and Asian Americans in the Democratic coalition. It reduces the electoral contribution of Jews to the Democratic party coalition (as gains in Florida are outweighed by losses in the Northeast), while increasing the importance of snowbird seniors who have relocated to warmer climes from blue states.
Large minority populations in growing red states mean that Republicans there will continue to need to be the near consensus party of Anglos in the South to win elections there. Outside the South, non-Hispanic whites are deeply split between the two major political parties, although the GOP has an edge with them.
The Republicans seem more unified politically at the moment, than the Democrats. But, the strongly geographic dimension of the divide between the Republican party's Christian right and its economic conservatives, and the large differences in political strategy between the "tribal" politics of Anglo ethnic identity in the South and the political strategy of issue driven intra-ethnic political contests elsewhere may ironically leave the GOP with more potential for schism into two different parties of the right, one dominant in each respective part of the country.
In contrast, the current big tent of the Democrats (which has shrunk somewhat by the defeat of many Blue Dogs), leaves the Democratic party seemingly more ideologically diffuse at the moment, the various factions within the Democratic party can't be decomposed nearly so easily on a regional basis. Democrats are more divided on tactics than they are on their political goals.
The American single member district plurality system can support more than two parties, so long as they are regional parties and there are no more than two strong political parties in any given area. But, the American electoral system strongly disfavors political party schism for geographically diffuse factions within a political party, even if that faction is substantial and ideologically coherent.
Third parties like the Green Party or the Libertarians are doomed in the absence of proportional representation elections. But, our system could support, for example, both a "21st century Whig Party" as a leading party of the right outside the South and areas of Mormon or Evangelical Christian religious dominance, centered on the economic establishment, and a "Christian Republican Party" that was strongly socially conservative but might have a more populist economic agenda than the existing Republican party, as a leading party of the right in current Republican strongholds.