Editor’s note: For more transit geekery, check out the follow up post detailing the demographics of Northwest transit riders.

Portland, OR has a national reputation as a transit powerhouse. Despite some recent funding woes—which are depressingly common for US transit systems—the City of Roses’ combination of bus, light rail, street car, and most recently aerial tram transit has earned national kudos. US News and World Report, for example, recently ranked Portland’s transit system as the fifth-best in the country, trailing cities like New York and Boston.

Yet as we’ve mentioned before, data from the US Census shows that Seattle has far more transit commuting than Portland.  It’s really not all that close: in Seattle, about 21 percent of workers got to their jobs on transit from 2006 through 2010. But in Portland, the figure is just 12 percent.

The chart above covers people who work in the city, no matter where they live. There’s a similar pattern for people who live in the city proper, regardless of where they work: whichever way you slice the numbers, the Emerald City just has more transit commuting than the Rose City.

In most other respects, the two cities’ commuting patterns are similar. Portland has more bike commuters than Seattle—which comes as no surprise, given Portland’s robust biking infrastructure and flatter terrain. But Seattle has more walkers than Portland; on net, the two cities have nearly identical rates of muscle-powered commuting. Similarly, the two cities have very similar rates of carpooling. The only substantial commuting difference boils down to this: Seattle has more transit riders, and fewer drive-alone commuters, than Portland.

Just to be clear: I’m not saying that transit in Portland is inherently worse (or better) than in Seattle. Strictly speaking, the story of transit commuting isn’t just about transit. It’s largely a story about land use. In part through accidents of geography and history, Seattle has a handful of highly concentrated job centers, particularly downtown and the University of Washington; and transit is a particularly effective commuting option in neighborhoods with high employment densities. And at the same time, high parking costs in Seattle’s downtown discourage drive-alone commuting.

Portland clearly has made a substantial commitment to its transit system. But in the end, even a nifty transit system only goes so far. If you really want to encourage transit commuting, you need to focus on land use. Maybe that’s why Vancouver, BC, beats both Seattle and Portland in transit commuting rates.