Washington-area neighborhoods in walking distance of Metro are wealthier and whiter than their surroundings, according to a new Census Bureau study. But for many places outside the District, living near Metro has become more affordable.

How earnings of workers who live near Metro and elsewhere have shifted. Click the image for definitions. Tables from the Census Bureau.

Working at the Census Bureau, Brian McKenzie can see data that privacy rules keep from other researchers. His new research paper is chock-full of interesting data.

McKenzie was able to compare surveys taken in 2006-08 and 2011-13, and compare DC residents to those who live in the five-county area of Alexandria, Arlington, Fairfax, Montgomery, and Prince George’s. Using the individual addresses of people who have jobs and answered Census surveys, he separated those who live on street blocks within a half-mile of Metro stations from those who live elsewhere.

This isn’t a perfect way of identifying who can walk to the train, but it’s far superior to what other researchers have been able to do.

Among McKenzie’s key findings is that more people are living near Metro, and more of them are riding the transit system. In five years the number of workers in walking distance of a station rose 23%. The working population living farther from Metro increased just 5% region-wide, and dropped slightly in the District. Over 15% of the region’s 1.8 million workers, including a majority of the 321,000 who live in DC, now have a short walk from home to Metro.

The data also show the increasing use of non-auto transportation, cycling even more than transit. This trend is strongest among DC residents who live near Metro. Although this population is growing rapidly, the number of drivers among them hardly changed, so that the percentage who drive to work alone plummeted from 30% to 25%.

Transit use in this group increased from 57,000 to 72,000, and the number of bicycle commuters soared from 3300 to 7900. Trends among other demographics are similar in direction, but slower.

Trends in travel mode to work.

The most widely noted finding of this study is the increasing affluence and whiteness near Metro. This, however, is essentially a DC phenomenon. In the surrounding counties, the income spread between walk-to-Metro housing and elsewhere is, if anything, shrinking.

All ethnic groups grew in absolute numbers near non-DC Metro stations; the share of both whites and blacks declined as Asians and Hispanics moved in faster. And where the percentage of these counties’ residents with income over $100,000 was 2.1% higher near Metro than elsewhere in 2006-08, the difference fell to 1.7% five years later. Most other income groups show a consistent pattern of shifts.

Because these changes fall within the margin of error, it’s not clear whether the difference between incomes near Metro and farther from it is really closing, but the gap is not growing wider as it is in the District.

New apartments and inclusionary zoning have helped with affordability

Why hasn’t Metro-accessible housing in the outer counties become less affordable? Most of the credit undoubtedly goes to the smart growth zoning that has opened up stations in Montgomery and Arlington Counties to new apartment construction. Builders there are required to include a percentage of more affordable units in new construction. And while newly built market-rate apartments in Bethesda or Clarendon aren’t cheap, they are (with the occasional exception) less expensive than the single-family houses nearby.

The District, meanwhile, lagged behind in enacting inclusionary zoning and then stalled on implementing it. And it has allowed little new construction near Metro in the upscale neighborhoods west of Rock Creek.

Demographic and cultural change may be the motive force behind shifting living patterns, but public policy makes a big difference in how things play out.