Let’s say that you run a small foodservice business that’s looking for a location in DC. Your business offers food throughout the day, but relies primarily on the high-volume, low-margin office lunch trade. Your best-performing locations are in 24-hour areas with high employment density, medium population density, and lots of students. Seeing as Washington is not exactly Cambridge, where should you seek out welcoming crowds?

Conveniently, the Census offers “OnTheMap,” which is a way to generate online maps showing employment density (and commute flows). Here’s an employment density map of downtown DC:

Note how steeply job density drops off along Massachusetts Avenue, the northwest boundary of DC’s CBD: density roughly halves with every single block.

Indeed, in the entire broader metropolitan region, there are only a handful of business districts that meet the median quintile of job density, like downtown Baltimore, Bethesda, Tysons Corner, Old Town Alexandria, and most curiously, an industrial estate in Springfield. However, these areas still have only 1/4 to 1/3 the job density found in downtown DC. As mentioned before, downtown DC has densities far beyond anywhere else in the region.

Population density maps are rather easier to find, and offer a useful contrast; sadly, there aren’t very many mixed areas with both lunch and dinner crowds. Right along the Mass Ave boundary is one option, particularly at the junctions where it’s most permeable (e.g., Dupont or Thomas Circle). Another intriguing possibility is NoMa: it’s one of a few neighborhoods where the 2010 density maps shown above would be significantly out-of-date, and the opening of Union Market has drawn a cluster of foodie businesses to the area.