Here are some nice visualizations of the demographic changes in Washington D.C over 10 years (2000-2010): http://datatools.urban.org/features/changingcities/#index
"Washington, DC, residents don't need census data to tell them what's obvious in their neighborhoods: the city is changing dramatically. But numbers can give us context. They can show us how shifts in population are reshaping the city and can help us prepare for changes to come.
In this series, we'll home in on changes from the past decade—2000 to 2010—when DC's population began growing again for the first time in 50 years. In this chapter, we look at demographic change, drilling down to wards and neighborhoods. Later, we'll explore changes in housing, crime, education, and more, using data from NeighborhoodInfo DCto tell the story of our changing city."