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
All states and U.S. territories
Maps and coordinates
County directory

San Joaquin County ZIP Codes

Browse all ZIP Codes, cities, and associated area codes registered in San Joaquin County.

County State ZIP Code City Area Codes
San Joaquin County CA 95391 Tracy 209, 350, 925
San Joaquin County CA 95686 Thornton 209, 279, 350, 916
Page 5 of 5

Geographic Map of San Joaquin County

Postal context

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.