There is a common perception in much of America that poor people ride public transit to work, while wealthier people drive. Here in the D.C. area, this is true—-to an extent. It’s the case in the District (where the average commuter makes $51,469, to just $45,771 for the average transit commuter), Arlington ($62,510 vs. $60,640), Alexandria ($56,080 vs. $52,592), and Prince George’s County ($41,447 vs. $36,747). But, as a new report on D.C-area commuters from the Center for Regional Analysis at George Mason University shows, in the outlying suburbs, the opposite is true.

Take Fairfax County, where the average transit commuter makes more than $10,000 more than the average commuter overall. Or Loudoun County, where the difference is more than $20,000. Or Prince William County, where the disparity is a whopping $23,269: $70,743 for transit commuters, $47,474 for all commuters.

What could account for these contrasting patterns? Here are a few possible explanations:

1. Commuters in the core take transit because they have to. Commuters in the outlying suburbs take transit because they can. 

According to the report, nearly half of D.C. residents who commute by transit don’t have a vehicle of their own. In the outer suburbs, less than three percent of transit commuters lack a vehicle. Those suburban commuters are choosing transit because it’s faster or cheaper or more convenient, not because they have no other option.

2. Transit access is valuable in the suburbs.

In the District, nearly everyone has access to some form of public transit. In the suburbs, it’s much rarer. Since transit can make for a more pleasant trip to work—-and, as AAA pointed out last week, can save a commuter a lot of money—-people are willing to pay extra to live near a Metro station, so wealthier people tend to have greater access.

3. The bus differential.

For most residents of the District, the nearest bus stop is closer to their homes than the nearest Metro station. Buses, for whatever reasons of socioeconomics or prejudice, are often considered a lower-class form of transportation. In D.C., the bus is the most convenient way for many people to get to work. In the outer suburbs, it’s very rare to take the bus to work. So the average income of D.C. (and inner-suburb) transit commuters is likely brought down by all those bus commuters, while the figures for the outer suburbs come almost entirely from Metro commuters, who may tend to be wealthier.

4. Suburban transit commuters are much more likely to be government workers.

According to the report, among D.C. residents, transit commuters and other commuters are about equally likely to work for the government. In the inner suburbs, there’s a slight difference: 32.5 percent of transit commuters are government employees, versus 24.6 percent of all commuters. But in the outer suburbs, the discrepancy is huge: 51.6 percent of transit commuters, to just 26 percent of commuters overall. That likely has something to do with the fact that government workers work largely in D.C., which has good transit access—-and, as the chart above shows, pays good salaries. As a result, the many high-paid executive-branch and Hill workers bring up the average income of transit commuters, while people working at the local mall or gas station are commuting by car. (The few who commute to those local jobs by transit, as the chart shows, make very little money.) Here in the District, on the other hand, people working blue-collar jobs are just as likely to take the bus or Metro to work as Hill staffers.

Images from the CRA report