Foster -- U.S. County in North Dakota Population (2000): 3759 Housing Units (2000): 1793 Land area (2000): 635.200527 sq. miles (1645.161743 sq. km) Water area (2000): 11.516196 sq. miles (29.826810 sq. km) Total area (2000): 646.716723 sq. miles (1674.988553 sq. km) Located within: North Dakota (ND), FIPS 38 Location: 47.464369 N, 98.894282 W Headwords: Foster Foster, ND Foster County Foster County, ND