Monmouth -- U.S. County in New Jersey Population (2000): 615301 Housing Units (2000): 240884 Land area (2000): 471.937793 sq. miles (1222.313221 sq. km) Water area (2000): 193.180213 sq. miles (500.334433 sq. km) Total area (2000): 665.118006 sq. miles (1722.647654 sq. km) Located within: New Jersey (NJ), FIPS 34 Location: 40.285874 N, 74.127063 W Headwords: Monmouth Monmouth, NJ Monmouth County Monmouth County, NJ