Essex -- U.S. County in Massachusetts Population (2000): 723419 Housing Units (2000): 287144 Land area (2000): 500.667108 sq. miles (1296.721801 sq. km) Water area (2000): 327.859826 sq. miles (849.153015 sq. km) Total area (2000): 828.526934 sq. miles (2145.874816 sq. km) Located within: Massachusetts (MA), FIPS 25 Location: 42.635475 N, 70.970827 W Headwords: Essex Essex, MA Essex County Essex County, MA