Springfield is a city in the state of Massachusetts, United States, and the seat of Hampden County. Springfield sits on the eastern bank of the Connecticut River near its confluence with three rivers: the western Westfield River, the eastern Chicopee River, and the eastern Mill River. As of the 2010 Census, the city's population was 153,060. As of 2018, the estimated population was 155,032, making it the third-largest city in Massachusetts, the fourth-most populous city in New England after Boston, Worcester, and Providence, and the 12th-most populous in the Northeastern United States. Metropolitan Springfield, as one of two metropolitan areas in Massachusetts (the other being Greater Boston), had a population of 692,942 as of 2010.