Prosser, WA -- U.S. city in Washington Population (2000): 4838 Housing Units (2000): 1800 Land area (2000): 4.300173 sq. miles (11.137396 sq. km) Water area (2000): 0.130666 sq. miles (0.338423 sq. km) Total area (2000): 4.430839 sq. miles (11.475819 sq. km) FIPS code: 56450 Located within: Washington (WA), FIPS 53 Location: 46.206921 N, 119.765612 W ZIP Codes (1990): 99350 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Prosser, WA Prosser