Description: This data set approximates the boundaries of United States Postal Service (USPS) ZIP code delivery areas within Prince George's County, Maryland. The polygon boundaries are based on actual delivery areas used by mail carriers and captured to follow parcel boundaries wherever possible, with some following street centerlines, political boundaries, and topographic features. Since neither the U.S. Postal Service nor the U.S. Census Bureau maintains official ZIP code boundary files or maps, the M-NCPPC created this file in order to be able to map data aggregated by ZIP code. Planning Department staff relied on the official USPS website database and regional post office staff to delineate areas within which letter carriers delivered mail with the same ZIP code. This data set includes all the standard type ZIP codes, as well as the unique ZIP codes for the NASA Goddard Space Center, the University of Maryland College Park, the Southern Maryland Processing and Distribution Center, and the Washington Bulk Mail Center. Where the P.O.-box-only type of ZIP code differs from the surrounding standard ZIP codes, they are captured symbolically at each post office as a circular shape ten feet in diameter.