Jefferson -- U.S. County in Kentucky Population (2000): 693604 Housing Units (2000): 305835 Land area (2000): 385.087715 sq. miles (997.372560 sq. km) Water area (2000): 13.487869 sq. miles (34.933418 sq. km) Total area (2000): 398.575584 sq. miles (1032.305978 sq. km) Located within: Kentucky (KY), FIPS 21 Location: 38.209237 N, 85.704021 W Headwords: Jefferson Jefferson, KY Jefferson County Jefferson County, KY