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

Cantilever bridge

A cantilever bridge is a bridge built using cantilevers, structures that project horizontally into space, supported on only one end. For small footbridges, the cantilevers may be simple beams; however, large cantilever bridges designed to handle road or rail traffic use trusses built from...

 that spans more than two miles (3 km) from Charlestown

Charlestown, Massachusetts

Charlestown is a neighborhood of Boston, Massachusetts, United States, and is located on a peninsula north of downtown Boston. Charlestown was originally a separate town and the first capital of the Massachusetts Bay Colony; it became a city in 1847 and was annexed by Boston on January 5, 1874...

 to Chelsea

Chelsea, Massachusetts

Chelsea is a city in Suffolk County, Massachusetts, United States directly across the Mystic River from the city of Boston. It is the smallest city in Massachusetts in land area, and the 26th most densely populated incorporated place in the country.-History:...

 over the Mystic River

Mystic River

The Mystic River is a river in Massachusetts, in the United States. Its name derives from the Wampanoag word "muhs-uhtuq", which translates to "big river." In an Algonquian language, "Missi-Tuk" means "a great river whose waters are driven by waves", alluding to the natural tidal nature of the...

 in Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

. The bridge is the largest in New England

New England

New England is a region in the northeastern corner of the United States consisting of the six states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, and Connecticut...

. It is operated by the Massachusetts Department of Transportation and carries U.S. Route 1

U.S. Route 1

U.S. Route 1 is a major north–south U.S. Highway that serves the East Coast of the United States. It runs 2,377 miles from Fort Kent, Maine at the Canadian border south to Key West, Florida. U.S. 1 generally parallels Interstate 95, though it is significantly farther west between...

. It was erected between 1948 and 1950 and opened to traffic on February 2, 1950, replacing the former Chelsea Street Bridge.