Route 51 is a bus route operated by the Maryland Transit Administration in Baltimore and its suburbs. The line currently runs from the center of Towson to the Inner Harbor in Downtown Baltimore, serving the Charles Street corridor. Route 51 replaced Route 11 on June 18, 2017 due to the BaltimoreLink bus system overhaul. As part of the Bus Network Improvement Project, the 11 was truncated to run between Towson and the Inner Harbor, with the eastern portion of the route served by the new Route 31, effective 22 February 2015.