01432 -- U.S. ZIP code Municipality (1990): AYER, Massachusetts All ZIPs for this municipality (1990): 01432 Population (2000): 8042 Housing Units (2000): 3470 Land area (2000): 11.651525 sq. miles (30.177310 sq. km) Water area (2000): 0.619747 sq. miles (1.605138 sq. km) Total area (2000): 12.271272 sq. miles (31.782448 sq. km) Located within: Massachusetts (MA) Location: 42.549821 N, 71.591363 W