Michael Barone has written a careful analysis of the present demographic shifts and their political implications.
Twenty years ago political analysts grasped the implications of the vast movement from Rust Belt to Sun Belt, a tilting of the table on balance toward Republicans; but with California leaning heavily to Democrats, that paradigm seems obsolete. What's now in store is a shifting of political weight from a small Rust Belt which leans Democratic and from the much larger Coastal Megalopolises, where both secular top earners and immigrant low earners vote heavily Democratic, toward the Interior Megalopolises, where most voters are private-sector religious Republicans but where significant immigrant populations lean to the Democrats. House seats and electoral votes will shift from New York, New Jersey and Illinois to Texas, Florida, Georgia, Arizona and Nevada; within California, House seats will shift from the Democratic coast to the Republican Inland Empire and Central Valley.
Demography is destiny. When I was in kindergarten in 1950, Detroit was the nation's fifth largest metro area, with 3,170,000 people. Now it ranks 11th and is soon to be overtaken by Phoenix, which had 331,000 people in 1950. In the close 1960 election, in which electoral votes were based on the 1950 Census, Michigan cast 20 votes for John Kennedy and Arizona cast four votes for Richard Nixon; New York cast 45 votes for Kennedy and Florida cast 10 votes for Nixon. In 2012, Michigan will likely have 16 electoral votes and Arizona 12; New York will have 29 votes and Florida 29. That's the kind of political change demographics makes over the years.