Sheriff Road–River Terrace Line

Route U4 provides daily service between Minnesota Avenue station and Sheriff Road NE & Lee Street NE (Sheriff Road) or 33rd Street NE & Blaine Street NE (River Terrace). Because the U4 route is a short Metrobus route with low passenger demand, U4 has almost always been assigned the smaller sized 30-foot buses, as opposed to the regular 40-foot sized buses WMATA typically uses on many of its Metrobus routes. However, route U4 occasionally uses 40 ft buses if the 30 ft buses are undergoing maintenance.

Route U4 operates out of Southern Avenue division during the weekdays and Bladensburg division during the weekends. The route mostly utilizes the 2012 Orion VII BRTs (3041-3044) out of Southern Avenue and 2006 30 ft Orion VII CNGs during the weekends but also regularly uses the XN40s based out of Bladensburg.

U4 originally operated as part of the "Sheriff Road-River Terrace" streetcar line, between the Deanwood & River Terrace neighborhoods of Northeast Washington D.C. The U4 streetcar line was later replaced by buses during the 1950s and eventually became a WMATA Metrobus Route on February 4, 1973 when WMATA acquired all four bus companies that operated throughout the Washington D.C. Metropolitan Area and merged them all together to form its own, "Metrobus" System. U4 kept operating on the same exact streetcar routing it had been operating on since 1949, even after becoming a WMATA Metrobus Route.[1]

• On September 5, 2017, a passenger was arrested after he spat on a U4 bus driver along Minnesota Avenue. The driver was taken to a hospital.[5][6]