Cambridge ( KAYM-brij) is a city in Middlesex County, Massachusetts, and part of the Boston metropolitan area as a major suburb of Boston. As of the 2020 United States Census, the city's population was 118,403, making it the fourth most populous city in the state, behind Boston, Worcester, and Springfield. It is one of two de jure county seats of Middlesex County, although the county's government was abolished in 1997. Situated directly north of Boston, across the Charles River, it was named in honor of the University of Cambridge in England, once also an important center of the Puritan theology embraced by the town's founders.