 B2 initially started off as a streetcar line in 1910, operating between Mount Rainier, MD, Municipal Place & Rhode Island Avenue & the Anacostia neighborhood of Southeast Washington D.C.The B2 streetcar line was later replaced by buses in 1923 and eventually became a Metrobus Route on February 4, 1973 when WMATA acquired four private bus companies that operated throughout the Washington D.C. Metropolitan Area and merged them all together to form its own, "Metrobus" System.Route B2 kept operating on the same exact routing as its streetcar route after.