03809 -- U.S. ZIP code Municipality (1990): ALTON, New Hampshire All ZIPs for this municipality (1990): 03809 Population (2000): 3550 Housing Units (2000): 2187 Land area (2000): 47.452611 sq. miles (122.901694 sq. km) Water area (2000): 0.498114 sq. miles (1.290109 sq. km) Total area (2000): 47.950725 sq. miles (124.191803 sq. km) Located within: New Hampshire (NH) Location: 43.478364 N, 71.223778 W