Boston Elevated Railway Company's streetcar No. 393 smashes through the warning gates of the open Summer Street drawbridge in Boston, Massachusetts, plunging into the frigid waters of Fort Point Channel, killing 46 people.

The Boston Elevated Railway (BERy) was a streetcar and rapid transit railroad operated on, above, and below, the streets of Boston, Massachusetts and surrounding communities. Founded in 1894, it eventually acquired the West End Street Railway via lease and merger to become the city's primary mass transit provider. Its modern successor is the state-run Massachusetts Bay Transportation Authority (MBTA), which continues to operate in part on infrastructure developed by BERy and its predecessors.

On November 7, 1916, a streetcar loaded with passengers ran off the open Summer Street Bridge, a retractile bridge, into Fort Point Channel near downtown Boston, Massachusetts, United States. Forty-six passengers were killed, making it the deadliest disaster in Boston's history until surpassed by the Cocoanut Grove fire in 1942.

The Summer Street Bridge is a retractile bridge built in 1899 in Boston, Massachusetts, over the Fort Point Channel. It still stands, but has served as a fixed bridge since 1959. This was the site of the Summer Street Bridge disaster in 1916.

Boston is the capital and most populous city of the U.S. state of Massachusetts. The city serves as the cultural and financial center of New England, a region of the Northeastern United States. It has an area of 48.4 sq mi (125 km²) and a population of 675,647 as of the 2020 census, making it the third-largest city in the Northeastern United States after New York City and Philadelphia. The larger Greater Boston metropolitan statistical area has a population of 4.9 million as of 2023, making it the largest metropolitan area in New England and the eleventh-largest in the United States.