Illinois

Across Illinois, GIS Map currently maps 70 cities and towns that together hold around 6,444,645 residents. The Prairie State is anchored by Chicago's skyline and surrounded by vast agricultural heartland. The most populous community is Chicago, with about 2,711,226 residents in Cook County, and it has an interactive street, satellite and topographic map. Aurora (179,898) and Naperville (150,692) follow. The state capital, Springfield, sits in Sangamon County.

County-level coverage in Illinois includes 102 official Census boundaries, each paired with local demographics. Cook County is the most populous, with about 5,182,090 residents. The highest median household income belongs to DuPage County at $112,096. By land area, McLean County is the largest at roughly 1,183 square miles. The youngest population, with a median age of 30.7, is found in Champaign County. Among mapped cities with at least 10,000 residents, Naperville reports the highest median household income at $155,105. All figures come from the U.S. Census Bureau's American Community Survey 2020-2024 five-year estimates.

Illinois's mapped cities sit at a wide range of elevations. Crystal Lake is the highest at about 910 feet above sea level, while Carbondale is the lowest at about 416 feet. Every mapped city observes Central Time. According to the USDA U.S. General Soil Map, Mollisols are the dominant soil order beneath 29 of the mapped city centers. Federal records list 27 government-owned and 175 leased properties in these cities, the most in Chicago. City maps let you switch on FEMA flood zones, USGS contours and land cover layers.

We also map 188 ZIP code areas in Illinois, each with its boundary and demographics. The most populated one has about 108,324 residents. The runner-up counts roughly 91,901 people. The densest packs about 47,547 people per square mile. Every page includes drawing and measuring tools plus a click-anywhere inspector that reports the county, ZIP, census tract, school district, flood zone and elevation of any point.