The Causeway Street Elevated began at the Canal Street Incline in parallel with the Charlestown Elevated tracks, turned southwest above Causeway Street with an elevated station at North Station in front of the Boston Garden, and then turned northwest above Lowell Street, before joining the Lechmere Viaduct at Leverett Circle.
The Causeway Street Elevated was one of the last pieces of elevated line constructed in Boston, and, except for a short section remaining at Lechmere, was the last section in service.