35603 -- U.S. ZIP code Municipality (1990): DECATUR, Alabama All ZIPs for this municipality (1990): 35601 35603 Population (2000): 26125 Housing Units (2000): 11238 Land area (2000): 70.329910 sq. miles (182.153623 sq. km) Water area (2000): 0.786666 sq. miles (2.037455 sq. km) Total area (2000): 71.116576 sq. miles (184.191078 sq. km) Located within: Alabama (AL) Location: 34.539072 N, 86.957329 W