03865 -- U.S. ZIP code Municipality (1990): PLAISTOW, New Hampshire All ZIPs for this municipality (1990): 03865 Population (2000): 7747 Housing Units (2000): 2927 Land area (2000): 10.623474 sq. miles (27.514669 sq. km) Water area (2000): 0.009171 sq. miles (0.023753 sq. km) Total area (2000): 10.632645 sq. miles (27.538422 sq. km) Located within: New Hampshire (NH) Location: 42.837189 N, 71.094451 W