Greenbelt, MD -- U.S. city in Maryland Population (2000): 21456 Housing Units (2000): 10180 Land area (2000): 5.982289 sq. miles (15.494056 sq. km) Water area (2000): 0.034679 sq. miles (0.089819 sq. km) Total area (2000): 6.016968 sq. miles (15.583875 sq. km) FIPS code: 34775 Located within: Maryland (MD), FIPS 24 Location: 39.000460 N, 76.888325 W ZIP Codes (1990): 20770 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Greenbelt, MD Greenbelt