The Canal Street incline (also Canal Street portal) was a ramp connecting two transit tunnels in Boston with surface and elevated lines. It was located in the Bulfinch Triangle between North Station and Haymarket Square in two blocks bounded by Canal Street to the west, Causeway Street to the north, Haverhill Street to the east, and Market Street to the south. The incline was the north end of the Tremont Street subway (which became the center of the MBTA Green Line) and the Washington Street Tunnel (which became the Orange Line). Built in 1898, it remained in use until 2004 when the last connecting line was moved underground.