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

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State directory

Illinois ZIP Codes

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

State	ZIP Code	City	County	Area Codes
IL	61436	Gilson	Knox County	`309`
IL	61437	Gladstone	Henderson County	`309, 319`
IL	61438	Good Hope	McDonough County	`309`
IL	61439	Henderson	Knox County	`309`
IL	61440	Industry	McDonough County	`309`
IL	61441	Ipava	Fulton County	`309`
IL	61442	Keithsburg	Mercer County	`309, 319`
IL	61443	Kewanee	Henry County	`309`
IL	61447	Kirkwood	Warren County	`309`
IL	61448	Knoxville	Knox County	`309`

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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.