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
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 61047 Leaf River Ogle County 779, 815
IL 61048 Lena Stephenson County 779, 815
IL 61049 Lindenwood Ogle County 779, 815
IL 61050 Mc Connell Stephenson County 779, 815
IL 61051 Milledgeville Carroll County 779, 815
IL 61052 Monroe Center Ogle County 779, 815
IL 61053 Mount Carroll Carroll County 779, 815
IL 61054 Mount Morris Ogle County 779, 815
IL 61057 Nachusa Lee County 779, 815
IL 61059 Nora Jo Daviess County 779, 815
Page 53 of 159

Geographic Map of Illinois

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.