Three major airports serve both suburban Maryland and the Washington, D.C., area. Baltimore-Washington International (BWI) Airport, 10 mi south of Baltimore off I-95 and Route 295, is closer to Montgomery and Prince George's counties than Ronald Reagan National Airport or Washington Dulles International Airport.
A taxi to Dulles or BWI airport is expensive, but BWI is well served by reasonable ground transportation. Washington Metropolitan Transit Authority (WMATA) has an express bus to the airport from its Greenbelt, Maryland, Metrorail station. All northbound Amtrak and Maryland State Penn Line trains from Washington's Union Station make a BWI stop, from which a free shuttle bus takes you to the terminal. Dulles is served by Washington Flyer bus every 30 minutes from the West Falls Church Metrorail station ($10), by Metrobus Route 5A express service ($6), and by van services like SuperShuttle ($35). The Washington Metropolitan Area Transit Authority (WMATA) operates express bus service between BWI and the Greenbelt Metro station. Buses run between 6 am and 11 pm weekdays, and 8:45 am and 11 pm weekends. Exact fare ($6) is required. BWI is also served by SuperShuttle. By taxi, expect to pay around $40 to Laurel, $65 to Silver Spring, and $73 to Bethesda. Free shuttle buses carry passengers between airline terminals and the train station at BWI. Amtrak and Maryland Rail Commuter Service (MARC) trains run between BWI and Washington, DC's Union Station and Prince George's County from around 4:30 am to 10:30 pm. The cost of the 30-minute ride to Union Station is $13 to $34 on Amtrak and $6 on MARC, which runs only on weekdays.