Westfield is a city located in Hampden County within the Pioneer Valley of western Massachusetts, United States. It lies at the western edge of the downfaulted Connecticut River Valley where the Westfield River emerges from the Berkshire Hills and flows through the center of the city toward the Connecticut River. The municipality is part of the Springfield Metropolitan Statistical Area and serves as a significant urban center on the fringe of the greater Northeast megalopolis, bordered by towns such as Southampton, Holyoke, and Agawam.