city, Suffolk county, eastern Massachusetts, U.S. A northeastern suburb of Boston, it lies on the estuary of the Mystic River and is joined to Charlestown by a road bridge. Settled in 1624 as Winnisimmet, it was renamed in 1739 for Chelsea, London. The city suffered massive fires in 1908 and 1973.

The city's economy was severely affected by the economic recession of the 1980s, and Chelsea was placed in receivership in 1991 by the state legislature. Nearly one-third of the population is Hispanic, and one-fourth of the residents live below the poverty level. Services and light manufacturing account for most employment. Inc. town, 1739; city, 1857. Pop. (1990) 28,710; (2000) 35,080.