Former DCist editor-in-chief Ryan Avent can often be found doing the yeoman’s task of sorting through census data on his blog, but he dug up a couple of real gems in a recently released stack of paper: July 2009 estimates released by the U.S. Census Bureau estimate that D.C. is but a few hundred people short of crossing the 600,000 mark. The upswing would make it the fifth fastest growing “state” in the union, if that’s the way you’d rather digest the information.

Hitting the big 600,000 might not seem like that big of a deal on the surface. But the number represents a real milestone after a nearly 50 year period of decline in D.C. — one which saw about a quarter of the city’s population leave — absolutely crippled the city’s population figures:

All population data from the the U.S. Census Bureau.

As Avent notes, this data is all the more encouraging when one considers that the District is finally seeing an upswing in migration numbers — more people are consciously moving here than leaving — rather than a increase due simply to people having more babies here. In addition to being a sign of Washington’s resurgence, these numbers are very good signs for many American cities who are currently in the shape D.C. was in the 80s, at the nadir of the population swing. (Here’s looking at you, Buffalo.) One can hope next year’s hard Census data continues the trend. Oh, and welcome to the District, all you newbies.