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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.

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St. Charles County ZIP Codes

Browse all ZIP Codes, cities, and associated area codes registered in St. Charles County.

County State ZIP Code City Area Codes
St. Charles County MO 63366 O Fallon 636
St. Charles County MO 63367 Lake Saint Louis 636
St. Charles County MO 63368 O Fallon 636
St. Charles County MO 63373 Portage Des Sioux 618, 636
St. Charles County MO 63376 Saint Peters 636
St. Charles County MO 63385 Wentzville 636
St. Charles County MO 63386 West Alton 314, 557, 618, 636
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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.