Downtown DC.

According to a US Census report, the District of Columbia’s daytime population, including commuters, swells to over 1,000,000. The difference between DC’s day and night populations is second greatest in the US.

The report dates from 2010 so the numbers are surely a bit different today. With DC’s (then) nighttime residential population of 584,400, its 1,046,036 daytime population represents a 79% increase. Among US counties, only New York County (Manhattan) has a larger percentage increase.

Arlington looks much the same. Its 26% increase in daytime population is 13th largest nationally. That’s higher than San Francisco on the list.

At the other end of the spectrum, two DC suburbs top the list of places with decreased daytime population. Dale City and Centreville in Northern Virginia both drop by over 40%, making them America’s ultimate bedroom communities. Montgomery County’s Germantown is Maryland’s highest entrant, and clocks in at #20 with a decrease of 31%.

Part of the explanation for this is simply where boundaries are drawn. For example, even though Houston has a large downtown with many commuters, it doesn’t appear on the increased daytime population list because the City of Houston annexed so many of its suburbs that more of its commuters still technically live within the city limits. Likewise, Houston’s Harris County is gigantic and more or less envelopes the entire metropolis, so there’s little difference at the county level either.

Geographically smaller jurisdictions in large metropolitan areas are disproportionately more likely to show up in this data. So it’s not a great comparison of commuting patterns across different metropolitan regions. But it’s nonetheless interesting to know.

 Cross-posted at Greater Greater Washington.