The L.A. Times "analyzed the 100 counties that the Census Bureau identified as the fastest growing between April 2000 and July 2003, the latest date for which figures were available. Stretched across 30 states, these counties grew cumulatively over that period by more than 16%, reaching a total population of 15.9 million."
It found that they "provided Bush a punishing 1.72 million vote advantage over Democrat John F. Kerry." That was almost half the president’s total margin of victory. Bush’s advantage in these counties was almost four times greater than the advantage they rpovided Bob Dole in 1996. In 2000 Bush won 94 of these counties, and with a smaller cumulative advantage of 1.06 million votes.

In 2004 Bush won about 63% of the votes cast in these 100 counties; he won 70% or more of the vote in 40 of them. I repeat, these are the fastest growing counties in the country; note that the Demo base of support (big urban counties) continue to lose population. Also note near the end of the article that Demo operatives and pollsters, so far, haven’t understood any of this, why it happened and what it means for their party.