Originally Posted by
jackal
IIRC, there's also a cheaper way to do it involving a bus from BWI to the Greenbelt Metro station, but it won't be as fast and is probably more confusing.
The Metrobus B30 (
www.wmata.com/bus/timetables/md/b30.pdf) runs every 40 minutes for $3.10. Takes you quickly from BWI to the Greenbelt Metro station - 35 minutes or so. Take the Green Metrorail line into the city and change to the Yellow line at any of the 9 stations where the Green and Yellow lines share the track (suggest doing it at Fort Totten station). Yellow line takes you directly to DCA. Metrorail cost varies with time of day - $2.35 outside of rush hour, $4.50 during rush hour.