Where does “the city” start and end? Some might say it’s the District line. But in reality, the lines between “city” and “suburb” are more unclear than you think.

“Urban” (blue) and “suburban” (green) parts of the DC area based on housing density. Map by the author. Click for a high-resolution version.

I got into an argument with someone at a happy hour a few years ago. Why? This dude said I lived in the suburbs, because Silver Spring was outside the District. Even if I was literally 1,000 feet from Eastern Avenue.

“But no,” I protested, “Silver Spring is an urban place! We have tall buildings! We’re a major transit hub! I walk everywhere!” He wouldn’t relent, and a normal bar disagreement got way more heated than it needed to be. (Thankfully, nobody got hurt.)

Many people would say the same: DC is “the city,” and everything else is “the suburbs.” But as our region grows and changes, the lines between “city” and “suburb” can get kind of blurry.

“Urban” and “suburban” are about “what,” not “where”

What makes a place “urban” or “suburban” isn’t just whether it sits on one side of a municipal boundary or another. The distinction is about physical characteristics, like population density, the mix of uses, and how it’s laid out. More often than not, urban places are older, built at a time when driving was less prevalent and places needed to support walking and transit use.

As a result there are places like Alexandria or Silver Spring that feel urban but happen to sit outside the District or even predate its founding. Meanwhile, there are parts of the District that were built more recently and feel very suburban, like Fort Lincoln in Northeast.

“It turns out that many cities’ legal boundaries line up poorly with what local residents perceive as urban,” wrote Jed Kolko, chief economist at Trulia, in a blog post a few months ago on FiveThirtyEight looking at how “suburban” some American cities are.

So how can you determine whether where the “urban” parts of a city or region really are? Kolko started by simply surveying people about whether they felt they lived in a rural, suburban, or urban place. He discovered that the housing density had a big impact on how residents saw where they lived.

Kolko found that at a density of 2,213 households per square mile, people started to say they lived in an urban place. That’s about the density of Falls Church. Below 102 households per square mile, they reported living in a rural place. Taking a few other data points into account, Kolko mapped several American cities and found that what many considered “the city” was actually really suburban, and vice versa.

He didn’t map the DC area, however. We don’t have the complete model he used, but I was able to map the region’s Census tracts based on household density.

Looking at the map, you can see a huge swath of blue in the District, representing areas with urban household densities. But that blue area hops across the Potomac River into Virginia, covering most of Arlington and Alexandria. It also extends into Maryland, encompassing Silver Spring, Takoma Park, and Hyattsville.

Beyond that, there are urban “clusters” outside the Beltway, in places like Wheaton and Rockville in Maryland and Merrifield and Reston in Virginia. Many of them overlap with Chris Leinberger’s map of “Walkable urban places” or WalkUPs. Meanwhile, the District has a fair share of “suburban” areas, like Palisades, Foxhall, and Crestwood in Northwest, Deanwood Kenilworth in Northeast, and Bellevue in Southwest.

Of course, this is just a map of housing density, which doesn’t really say anything about urban form: places that aren’t just dense, but have a street grid that makes it easy to walk and a mix of housing, shops, and other uses. Some of the urban places outside the District have those things. Others, like Fairland in eastern Montgomery County, have the population density but are really just dense suburbs, designed for driving and lots of it.

What else do you see in this map?

Dan Reed (they/them) is Greater Greater Washington’s regional policy director, focused on housing and land use policy in Maryland and Northern Virginia. For a decade prior, Dan was a transportation planner working with communities all over North America to make their streets safer, enjoyable, and equitable. Their writing has appeared in publications including Washingtonian, CityLab, and Shelterforce, as well as Just Up The Pike, a neighborhood blog founded in 2006. Dan lives in Silver Spring with Drizzy, the goodest boy ever.