Plainfield, IA -- U.S. city in Iowa Population (2000): 438 Housing Units (2000): 202 Land area (2000): 0.325066 sq. miles (0.841917 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 0.325066 sq. miles (0.841917 sq. km) FIPS code: 63210 Located within: Iowa (IA), FIPS 19 Location: 42.844652 N, 92.534623 W ZIP Codes (1990): 50666 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Plainfield, IA Plainfield