During this exact time, K6's routing between Mount Rainier and Chillum was replaced by DC Transit's East Riverdale - Cheverly Line Routes B4, B6, and B8 were extended from their original terminus at Mount Rainier to Chillum.

[4] Then, eventually during the early 1970's when DC Transit's East Riverdale - Cheverly Line Routes B4, B6, and B8 were discontinued, B2 was extended from its original terminus at Mount Rainier, to Chillum in order to replace their routing between Mount Rainier and Chillum.

On February 19, 1978, shortly after the Takoma station opened, B2 was truncated to only operate between Mount Rainier, Maryland and Anacostia.

F2 operated on the same exact routing as B2 between Mount Rainier and Chillum, only with the exception that it was extended to the Takoma station, via Eastern Avenue NE/NW, and Carroll Street NW.

F1 had a prior incarnation as the Avondale - Federal Triangle Express Line, which operated between Avondale and Federal Triangle as a DC Transit Route and eventually became a WMATA Metrobus Route on February 4, 1973, which ultimately got discontinued on February 19, 1978.