Track 61 is an industrial rail terminal track in South Boston, Massachusetts, also known as the Boston Terminal Running Track. Track 61 is the last remnant of the vast rail yards that once covered much of the South Boston waterfront. Track 61 legally begins at Summer Street, while the line from Bay Junction to Summer Street is the Boston Terminal Running Track and Terminal Yard. However, the names are frequently used interchangeably.

The Red Line is a rapid transit line operated by the Massachusetts Bay Transportation Authority (MBTA) as part of the MBTA subway system. The line runs south and east underground from Alewife station in North Cambridge through Somerville and Cambridge, surfacing to cross the Longfellow Bridge then returning to tunnels under Downtown Boston. It continues underground through South Boston, splitting into two branches on the surface at JFK/UMass station. The Ashmont branch runs southwest through Dorchester to Ashmont station, where the connecting light rail Ashmont–Mattapan High Speed Line continues to Mattapan station. The Braintree branch runs southeast through Quincy and Braintree to Braintree station.