The Metropolitan Washington Transportation Planning Board is having a meeting tomorrow on the "Changes in Commuting Patterns in Metropolitan Washington Region from 2000-2011". As we already knew, bike commuting is up, and in some places it is up a lot. Regionally, it is up from 0.3% of mode share to 0.7%, which moves biking out of sole possession of last place, into a tie for last place with "Other". But if you look at the urban core, you see a more dramatic increase over the last decade.
There are a lot of caveats to this data, like using small numbers, but nonetheless we see more than a doubling in DC and Arlington since 2000 and a tripling in Alexandria over the same time. The number of bike commuters in the area increased by about 11,000, about 60% of that by people who both live and work in DC. Other increases were for commuters within Montgomery County and between DC and Arlington. And this was only during CaBi's first full year.
And that change has been coming almost entirely out of driving. Both single occupancy vehicle use and carpooling are down, while transit, walking and working at home are all up.