21237 -- U.S. ZIP code Municipality (1990): ROSEDALE, Maryland All ZIPs for this municipality (1990): 21237 Population (2000): 25414 Housing Units (2000): 11859 Land area (2000): 11.717077 sq. miles (30.347090 sq. km) Water area (2000): 0.051923 sq. miles (0.134481 sq. km) Total area (2000): 11.769000 sq. miles (30.481571 sq. km) Located within: Maryland (MD) Location: 39.332240 N, 76.503657 W