The Census Bureau has released population estimates as of July 2008. The trends remain the same, with a little bit of flutter around the edges. That is:
In 1960, the Midwest and Northeast comprised more than half the nation's population, with the West and South just under half. Now, the West and South make up 60 percent of the population; the Midwest and Northeast just 40 percent.
Of major-population states, Michigan has really been taking it on the chin for decades now.
Michigan had as many as 19 seats in the U.S. House of Representatives as late as 1982. But it lost one seat in advance of that's year's election; two in the 1990s, and one following the 2000 census.
More here and below.