OK, one more post and I’ll take off my data-geek hat (which doesn’t fit very well, anyway). First a quick recap: On Wednesday, the Transportation Planning Board released a study finding, among other things, that “about 90% of the workers added to the District’s labor force between 2000 and 2011 both lived and worked in DC.” That appeared to imply that 90 percent of people taking jobs in D.C. were also choosing to live in D.C., but the TPB later clarified that in fact it meant 90 percent of the net new workers living in D.C. took jobs in D.C.

So what’s the data on the phenomenon I was truly curious about? This morning, I spoke with the TPB’s Robert Griffiths to get an answer.

Over the period from 2000 to 2011, he says, the District added 129,800 new workers—-and to avoid confusion, I’ll clarify: 129,800 new people working in the District—-and 41,200 of these people were District residents. That means 31.7 percent of new D.C. workers also chose to live in D.C.—-a far cry from 90 percent. But it’s still an increase over prior numbers. In 2000, just 29 percent of D.C. workers lived in D.C. By 2011, that figure had nudged up to 29.4 percent.

Griffiths argues that the other statistic—-the percentage of D.C. residents who also work in D.C.—-is just as telling. “From my perspective, I still think the original statistic is important,” he says. “In most other jurisdictions [in the region], it’s only about half of the residents that work in the jurisdiction they live in.”

That might not be a fair comparison: It’s to be expected that more people work in the hub city of a metropolitan region than in the suburbs. But Griffiths says that only about 75 percent of workers living in D.C. overall have jobs in D.C., so the 90 percent figure for the past decade represents real growth in this area.

As for the percentage of people working in D.C. who live in D.C., he says that figure is skewed downward by the lack of affordable housing in the city. “I think you’d find a lot more workers choosing to live in the District if they could find housing they could afford,” he says.

Graph from the TPB study