Cambridge is a city in Middlesex County, Massachusetts, in the United States. It is a major suburb in the Greater Boston metropolitan area, located directly across the Charles River from Boston. The city's population as of the 2020 U.S. census was 118,403, making it the largest city in the county, the fourth most populous city in the state, behind Boston, Worcester, and Springfield, and ninth most populous city in New England. It was named in honor of the University of Cambridge in England, which was an important center of the Puritan theology that was embraced by the town's founders.: 18