There are three major airports serving the Washington Metropolitan Area:
Dulles International Airport (IAD)
Major airport for international airlines. About 25 miles west of DC; accessible by bus, bus/metro, shuttle, or taxi
Reagan National Airport (DCA)
Serves mostly domestic airlines. Easily accessible by a short metro ride.
Baltimore Washington International Airport (BWI)
About 35 miles north-east of DC. Amtrak
has frequent trains to and from BWI to Washington DC. The Washington Open can be reached by Metro or cab from the Amtrak station.
Train Information: Amtrak
Buses and Metro Trains: Washington Metropolitan Area Transit Authority