31091 -- U.S. ZIP code Municipality (1990): UNADILLA, Georgia All ZIPs for this municipality (1990): 31091 Population (2000): 3870 Housing Units (2000): 1239 Land area (2000): 84.487334 sq. miles (218.821182 sq. km) Water area (2000): 1.096094 sq. miles (2.838870 sq. km) Total area (2000): 85.583428 sq. miles (221.660052 sq. km) Located within: Georgia (GA) Location: 32.244730 N, 83.720754 W