The Census Bureau has a breakdown of population trends for US cities with populations of over 100,000 (.xls file). 74 of these cities saw a decline in population from June 2006-June 2007. Of those 74 cities, 21 are in California, 8 are in Florida, 4 are in Michigan. Rounding out the bottom is Columbus, Georgia.
The city with the greatest percentage gain was New Orleans, which isn't surprising since people are returning to the Crescent City after Katrina. The city with the greatest real increase in population was Houston. And based on other census data, Harris County alone has seen an additional 250,000 people over the past 3 years.
I keep telling ya, it's like 1980 all over. The energy bubble is gonna pop, Houston's gonna get hammered within 2-3 years. I don't believe the "It's different this time, really!" hype any more than I bought the Nasdaq or "real estate can only go up" hype. The only difference between now and 1980 is they aren't throwing up quite as many skyscrapers downtown. There are no plans for super-tall buildings. Otherwise, things are the same. Gross overbuilding of office warehouse complexes, way too many strip shopping centers (many of which are vacant), too many cookie cutter houses.