U.S. POSTAL CODE DIRECTORY

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Directory coverage 42,735 ZIP Code records

Illinois Zip Codes



Illinois Illinois is the 25th most extensive and the 5th most populous of the 50 United States, and is often noted as a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal, timber, and petroleum in the south, Illinois has a broad economic base. Illinois is a major transportation hub. The Port of Chicago connects the state to other global ports from the Great Lakes, via the Saint Lawrence Seaway, to the Atlantic Ocean; as well as the Great Lakes to the Mississippi River, via the Illinois River. For decades, O Hare International Airport has ranked as one of the world s busiest airports. Illinois has long had a reputation as a bellwether both in social and cultural terms and politics.

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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Map of Illinois

ZIP codes are a system of postal codes used by the United States Postal Service (USPS) since 1963. The term ZIP, an acronym for Zone Improvement Plan, is properly written in capital letters and was chosen to suggest that the mail travels more efficiently, and therefore more quickly, when senders use the code in the postal address. The basic format consists of five decimal numerical digits. An extended ZIP+4 code, introduced in the 1980s, includes the five digits of the ZIP code, a hyphen, and four more digits that determine a more precise location than the ZIP code alone. The term ZIP code was originally registered as a servicemark (a type of trademark) by the U.S. Postal Service, but its registration has since expired.

ZIP codes designate only delivery points within the United States and its dependencies, as well as locations of its armed forces. There are no ZIP codes reserved for designating mail bound for foreign destinations (with the exception of U.S. military units stationed outside of the United States), and therefore, international outbound mail should not include a ZIP code in the delivery address. The last line of a foreign address must only show the name of the country of destination.

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