Middlesex -- U.S. County in Massachusetts Population (2000): 1465396 Housing Units (2000): 576681 Land area (2000): 823.457968 sq. miles (2132.746255 sq. km) Water area (2000): 24.084081 sq. miles (62.377480 sq. km) Total area (2000): 847.542049 sq. miles (2195.123735 sq. km) Located within: Massachusetts (MA), FIPS 25 Location: 42.459085 N, 71.275566 W Headwords: Middlesex Middlesex, MA Middlesex County Middlesex County, MA