Combined, Washington-Baltimore now outsizes Chicago as America’s third largest metropolis
Washington and Baltimore seen from the International Space Station by NASA astronaut Mark T. Vande Hei.
There are many ways to measure the population of regions. According to one that combines Washington & Baltimore, our region has passed Chicago to become the third largest metropolis in the United States.
For most of the past century or so, the United States’ three largest cities have been, unshakably, New York, Los Angeles, and Chicago. That’s still true according to most measures:
- Most populous municipalities: NY, LA, Chicago (DC is 23rd)
- Most populous metropolitan areas: NY, LA, Chicago (DC is 6th)
- Most populous urbanized areas: NY, LA, Chicago (DC is 8th)
- Most populous media markets: NY, LA, Chicago (DC is 9th)
But in one measure, Combined Statistical Areas (CSAs), that logjam just broke. CSAs combine adjacent metropolitan areas with shared commuter markets. If a high enough percentage of commuters in one metro area commute into another, you get a CSA.
Washington and Baltimore are combined. So is Los Angeles and its Inland Empire of Riverside & San Bernardino. So are San Francisco and San Jose, Boston and Providence, Detroit and Flint, Cleveland and Akron, Denver and Boulder, and 165 other combinations nationwide. The Census does combine Chicago into a CSA with Ottawa, IL, Kankakee, IL, and Michigan City, IN, but nearby Milwaukee doesn’t make the cut.
And according to that measurement method, the 2021 Census estimates show Washington-Baltimore surpassing Chicago for the first time.
Ten most populous CSAs
Largest CSAs. Image by US Census.
The different methods aren’t necessarily better or worse than one another. They simply measure different things.
Few if anyone would claim Washington is in any way the 3rd largest US city. But CSAs are one of many different objective measurements of an urban aggolomeration’s population, and the standard says what it says.