Washington Metropolitan Area Transit Authority is the principal public transport operator in Washington DC and immediate area. The Silver Line runs from Dulles International Airport and takes about 50 mins to get to downtown Washington DC. Click Here for the WMATA Website.
Finding a Metro Station
At the airport, the Metro station is well signposted once you get through Customs.
Once in Washington DC, Tall brown columns with a large M identify the station entrance. Colour stripes on the column show the lines that serve the station.
Paying the Fare
Fares are based on length of trip and entry time, and are subject to change during special events. Due to these caveats, I would recommend buying a 3-day ($28.00) or 7-day ($58.00) pass, depending on the length of visit.
You can also just add $ value to the card and app, and as you have to tap in and tap out of stations, it works out your fare and reduces your credit accordingly.
You will need to load the pass or $ value on a SmarTrip card, which can be purchased from a farecard machine at any Metro Station or downloading the SmarTrip app to your phone and purchasing via the app. I downloaded the app prior to getting to Washington and purchased a pass and it activated on first scan.
One other reason to use a SmarTrip card or app, which also covers busses in Washington DC, is if you transfer from Bus to Metro or vice versa, is that you get free or discounted fares for 2 hours after you start your journey.