Allen -- U.S. County in Kansas Population (2000): 14385 Housing Units (2000): 6449 Land area (2000): 503.006671 sq. miles (1302.781243 sq. km) Water area (2000): 2.175619 sq. miles (5.634828 sq. km) Total area (2000): 505.182290 sq. miles (1308.416071 sq. km) Located within: Kansas (KS), FIPS 20 Location: 37.886958 N, 95.344996 W Headwords: Allen Allen, KS Allen County Allen County, KS