ZIP Codes in Illinois
Illinois's ZIP codes cover a state defined almost entirely by one city - Chicago and its sprawling metro area account for well over half of the state's roughly 12.5 million residents, leaving the rest of Illinois as a long stretch of farmland running south toward the Mississippi River and the borders with Missouri and Kentucky. Few states show as sharp a population divide between one dominant metro region and the rest of the state.
How ZIP Codes Are Organized Across the State
Illinois's ZIP codes fall within the 60000–62999 range under the USPS system. Chicago itself occupies the lower end around 606xx, with the surrounding suburban collar counties spreading through 600xx–601xx. Rockford, in the north, sits near 611xx, while Springfield, the state capital, and the more rural downstate region carry codes further along toward 627xx and 629xx.
Illinois's Major Metro Areas by Population
The chart below makes the scale of Chicago's dominance clear - no other Illinois city comes close to its population, even combined.
Chicago's ZIP codes cover one of the largest and most economically diverse cities in the country, from the dense high-rise core of the Loop to residential neighborhoods stretching across the city's famous grid, plus a huge ring of suburban collar counties that continue to grow even as the city's own population has leveled off. Springfield, the state capital, sits far to the south and carries a much smaller, government-and-history-focused economy centered around its status as Abraham Lincoln's adopted hometown. For a wider comparison, our full US ZIP code directory shows how Illinois's ranges fit alongside every other state.
Downstate Illinois and Agriculture
South of the Chicago metro area, "downstate" Illinois shifts quickly into farmland, with corn and soybeans dominating the landscape across most rural ZIP codes. Peoria and Champaign-Urbana, home to the University of Illinois, stand out as the region's main population centers, but even these cities are dramatically smaller than the Chicago metro. This agricultural stretch continues south toward Missouri and the Mississippi River, sharing a similar Midwest farming character with ZIP codes across the state line.
The Chicago Collar Counties
Ringing the city itself, Illinois's collar counties - DuPage, Lake, Will, Kane, and McHenry - have absorbed much of the region's population growth over recent decades, with ZIP codes here reflecting a mix of established suburbs and newer development pushing further out from the urban core. These suburbs sit close to the border with Wisconsin in the north and Indiana to the east, both of which share commuter ties into the broader Chicago metro economy.
Why ZIP Codes Matter Beyond Mail
In Illinois, ZIP codes carry particular weight in Chicago's real estate market, where boundaries can mean sharply different property taxes and school district quality even between adjacent neighborhoods. Insurance companies use ZIP-level data extensively given Chicago's position as a major national insurance industry hub. And agricultural businesses downstate rely on ZIP codes to coordinate grain and livestock shipping logistics across the state's extensive rail network.
Finding the Right ZIP Code
Use the list below to browse Illinois's ZIP codes by city, county, or population - sorted so the most populous areas surface first. Each entry links through to a detailed page with additional demographic data. If you're trying to identify the ZIP code for a specific address rather than browsing by city, the search tool at the top of this page will get you there faster than scrolling through the full list.
Frequently Asked Questions
How many ZIP codes does Illinois have?
Illinois has well over a thousand ZIP codes, heavily concentrated in and around the Chicago metro area, with far fewer covering the state's largely rural downstate region.
What ZIP code range does Illinois use?
Illinois ZIP codes generally fall between 60000 and 62999, with Chicago toward the lower end and downstate Illinois further along the range.
Which Illinois city has the most ZIP codes?
Chicago and its surrounding collar counties account for the vast majority of Illinois's ZIP codes, given how heavily the state's population concentrates around the metro area.
Can I look up an Illinois ZIP code by city name?
Yes, use the search tool on this page or browse the full list below, which is organized by city and sorted by population.
Whether you're relocating to the Chicago metro area, researching property downstate near Springfield or Champaign, or simply trying to pin down the right ZIP code for a specific Illinois address, the data below covers every corner of the state.