U.S. postal lookup

U.S. ZIP Codes Database 2026

Search by ZIP code, city, county, or state and find clear postal details with maps, time zones, and area code data.

42,735 verified records
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Iowa ZIP Codes

Complete postal directory, details, and geographic map for the State of Iowa.

State ZIP Code City County Area Codes
IA 51054 Sergeant Bluff Woodbury County 402, 531, 712
IA 51055 Sloan Woodbury County 402, 531, 712
IA 51056 Smithland Woodbury County 712
IA 51058 Sutherland O'Brien County 712
IA 51060 Ute Monona County 712
IA 51061 Washta Cherokee County 712
IA 51062 Westfield Plymouth County 605, 712
IA 51063 Whiting Monona County 402, 531, 712
IA 51101 Sioux City Woodbury County 712
IA 51102 Sioux City Woodbury County 712
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About U.S. ZIP Codes

ZIP codes are a United States Postal Service system introduced in 1963 to make mail routing more accurate and efficient. The standard format uses five digits, while ZIP+4 adds four more digits for a more precise delivery segment.

ZIP codes cover the United States, its territories, military mail routes, and other USPS delivery points. This directory organizes that data for practical lookup by ZIP code, city, county, and state.