We're planning week-long family vacation to D.C. the first week of October. What would be the cheapest mode of transportation from the airport in Baltimore (4 people)? Thanks!

There's a train station right at or next to the airport and a commuter rail to Union Stat. DC. Assuming you don't mind shlepping a lot of luggage onto the shuttle to the train station and then on and off the train, it is certainly the cheapest. Otherwise, there are some shuttle van/limo services. See: http://www.bwiairport.com/frames/1_washington.html

Thank you, I will check into that.

The commuter train (MARC) that Chooch writes of doesn't run weekends. However, if you want cheap, you can catch the B30 Metrobus right at the airport ($2 - exact amount!) which takes you to the Greenbelt Metro Station. If it's weekend, or after 9:30am weekdays, buy the $5 Metro visitors pass for unlimited Metro travel. Actually, since you're gonna be there a week, buy the 7 day pass for $17 ... go to www.metroopensdoors.com and purchase your passes in advance.

It won't be pleasant lugging your baggage on and off and on again if you use trains, buses and subway. Also, all prices will be multiplied by four. There are several kinds of shuttle buses and vans that go to specific areas of the city or suburbs. We took one from Dulles to our Maryland suburb that said $26 in big letters on the outside of the van. Because there were two of us going to one address, the driver cut the price in half for one of us. With four going to the same hotel, you can try to negotiate a good price. Of course, it will be more than train-then-subway (Metro), but MUCH more convenient with luggage.

Yes, I know your travelling from BWI. They have their vans and shuttles too. If you have hotel reservations, you might phone the hotel to ask for suggestions.