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Illinois — United States

Welcome to the postal codes directory for Illinois, United States. As a prominent region in United States, Illinois contains 42 major cities indexed. Our platform provides comprehensive zip codes, neighborhood directories, and simulated local phone number generation rules for developer form testing and compliance verification.

42 Total Cities Indexed
ILLINOIS Region Code
🔍 Showing 42 cities

Available Cities

42
Albany Atlanta Aurora Bismarck Bridgeport Buffalo Burlington Charleston Chicago Columbia Concord Dover El Paso Evansville Frederick Greenville Hartford Henderson Jacksonville Knoxville Lansing Lexington Lincoln Louisville Madison Manchester Montgomery Nashville New Haven Newark Oakland Omaha Raleigh Richmond Rochester Rockford Rutland Salem San Jose Springfield Topeka Wilmington

Frequently Asked Questions

Regional Divisions & Cities
Illinois encompasses diverse geographical zones and municipal areas. This platform indexes 42 major cities in Illinois, linking each city to its postal codes, neighborhoods, and regional phone area codes.
State-Level Telecom Infrastructure
Under the NANP system, Illinois is allocated several distinct area codes covering specific counties and metropolitan districts. Select a city to explore local dialing overlays and to generate valid mock phone patterns.
How to look up the exact postal code for a specific district or street under Illinois?
You can select the corresponding city from the list above. On the city page, we provide a complete mapping table of districts, streets/neighborhoods, and their exact postal codes. You can also use the search bar at the top to instantly locate a street or neighborhood.