The D.C. Transit System is the public transportation system in Washington, D.C., and its surrounding areas. It is commonly referred to as METRO, which is the five-letter solution to this crossword puzzle. METRO operates a network of bus, rail, and paratransit services that serve the District of Columbia, Maryland, and Virginia. METRO is the second busiest rapid transit system in the United States, with an average weekday ridership of over 700, 000 passengers.