High Quality Content by WIKIPEDIA articles! The Maurice J. Tobin Memorial Bridge (formerly and still sometimes referred to as the Mystic River Bridge or less often the Mystic/Tobin bridge) is a cantilever truss bridge that spans more than two miles (3 km) from Charlestown to Chelsea over the Mystic River in Massachusetts. The bridge is the largest in New England. It is operated by the Massachusetts Department of Transportation and carries U.S. Route 1. It was erected between 1948 and 1950 and opened to traffic on February 2, 1950, replacing the former Chelsea Street Bridge. The 36-foot (11 m) wide roadway has three lanes of traffic on each of the two levels with Northbound traffic on the lower level and Southbound traffic on the upper level.