High Quality Content by WIKIPEDIA articles! The Green Line is one of five heavy rail subway lines that constitute the Washington Metro rapid transit system in the Washington, D.C., metropolitan area. The Green Line consists of 21 stations, with termini at Branch Avenue and at Greenbelt. The Green Line runs through Prince George`s County, Maryland, and the District of Columbia. It was the last line in the original Metrorail plan to be constructed, and is one of three north–south lines through the city of Washington. It shares four stations with the Yellow Line during rush hour service (nine stations during off-peak hours), one station with the Blue and Orange lines, and two stations with the Red Line.