An extension along Belair Road was built by the Central Passenger Railway in the late 1890s, branching off their Preston Street Line via Milton Avenue, and the Baltimore, Gardenville and Bel Air Electric Railway later opened an extension to Overlea.

An extension of the Edmondson Avenue Line was built north along Poplar Grove Street and Bloomingdale Road to Walbrook by the Baltimore and Powhatan Railway and west along Windsor Mill Road by the Gwynn Falls Railway.

In 1998, due to low ridership, Kingsville service was shortened to Perry Hall, and reduced to just seven trips daily on weekdays.

In 2005, as part of the Greater Baltimore Bus Initiative, a comprehensive overhaul plan for the region's transit system, MTA proposed to eliminate all service north of Overlea.

In 2003, due to the anticipated closure of the Forest Park Avenue bridge, Route 15 was modified in the Windsor Hills area.

Route 68 would have been converted into a feeder bus that would have operated between Security Square Mall and the Mondawmin Metro Subway Station.

Route 15 would no longer have operated west of Walbrook Junction, and the streets of Windsor Hills would not have had any bus service.

Protests included a 73-year-old man who complained that removing bus service from Forest Park Avenue and being forced to walk a greater distance to reach the nearest line could be life-threatening.