01451 -- U.S. ZIP code Municipality (1990): HARVARD, Massachusetts All ZIPs for this municipality (1990): 01451 Population (2000): 5000 Housing Units (2000): 1808 Land area (2000): 23.078722 sq. miles (59.773613 sq. km) Water area (2000): 0.049499 sq. miles (0.128201 sq. km) Total area (2000): 23.128221 sq. miles (59.901814 sq. km) Located within: Massachusetts (MA) Location: 42.505928 N, 71.588803 W