Building on what Eric wrote:  throughout the late 1990s, the Census Bureau emitsated that the District was hemorrhaging  population, right up to the 1999 estimate.  Lo and behold, when they actually conducted the Census in 2000, it turned out that the 1999 estimate was off by tens of thousands of people: in 1999 the Census Bureau emitsated the District\'s population was  519,000; the 2000 Census counted 572,000 people in the District!!!  They were WAY OFF in 1999.  I write this not to trash the Census Bureau but to note that their estimates can be quite suspect.  In the case of urban areas, it seems that their methodology, at least in 1990s, was biased against urban areas.  So, do not be surprised if the actual 2010 Census count is much higher than this 2009 estimate.