63534 -- U.S. ZIP code Municipality (1990): CALLAO, Missouri All ZIPs for this municipality (1990): 63534 Population (2000): 840 Housing Units (2000): 517 Land area (2000): 75.646872 sq. miles (195.924490 sq. km) Water area (2000): 0.614704 sq. miles (1.592075 sq. km) Total area (2000): 76.261576 sq. miles (197.516565 sq. km) Located within: Missouri (MO) Location: 39.741800 N, 92.635827 W