Businesses in Illinois: how to look one up, 322,415 workplaces by county and the state's biggest headquarters

Use this page to look up an Illinois business, check that it's legitimate, or size a market in one part of the state. It lists the state and city records to search, the Census count by county and industry, the largest companies headquartered in Illinois with figures from their filings, and a worked example in the logistics corridor south and west of Chicago.

How to look up a business in Illinois

The Chicago file is the useful download: 53,521 current licenses held by 36,332 license accounts as of 29 October 2026. One business can hold several licenses at one address, so count accounts, not rows. Outside Chicago, each city or village licenses businesses its own way.

To vet a supplier, confirm the entity is active with the Secretary of State, check the IDFPR license if its trade needs one, and for a Chicago business confirm its city license at the address where it operates.

How many businesses are in Illinois

That is 275,292 establishments with 1 to 19 employees, 38,451 with 20 to 99 and 8,672 with 100 or more. County Business Patterns counts every location with a payroll, so multi-site companies count once per site, and it leaves out the self-employed. Employment is for mid-March 2023.

Where Illinois businesses are

Cook County alone has 41.7% of the state's establishments and 44.0% of its jobs. Downstate counties have fewer but bigger workplaces: Peoria's average of 24.7 employees, McLean's 21.7 and Rock Island's 21.5 all beat Cook's 18.5. The table shows the state's seven largest counties and three downstate counties with unusually big workplaces.

What Illinois businesses do

Average pay is our calculation. Two lines show what sets Illinois apart: 225,210 people work in corporate, subsidiary and regional managing offices, the headquarters jobs of a state with dozens of large companies, and transportation and warehousing has 20,586 establishments, the rail, trucking and distribution hub around Chicago.

The largest companies headquartered in Illinois

Revenue and city come from each company's latest 10-K. Illinois Tool Works ($16.04 billion), CNA Financial ($14.99 billion), Arthur J. Gallagher ($13.94 billion), Ulta Beauty ($12.39 billion) and Motorola Solutions ($11.68 billion) are next. Downstate, beyond Deere, the public headquarters are smaller: RLI, the specialty insurer in Peoria ($1.88 billion), and Horace Mann in Springfield ($1.70 billion).

Some familiar names aren't ranked. LKQ's 10-K for 2025 gives Antioch, Tennessee as its principal executive office, and Kraft Heinz's gives Pittsburgh. Caterpillar's gives Irving, Texas. For the Chicago metro's top 30 and the full list of who's left, see the biggest companies in Chicago.

Prospecting Illinois's logistics corridor

Will County, along I-80 and I-55 south and west of Chicago, has more warehouse jobs than Cook County: 203 warehousing and storage establishments employing 27,224 people, an average of 134 per site.

Illustrative example. The company, rates and results are fictional; the counts are from County Business Patterns.

Prairie Dock Safety (prairiedock.example) inspects and repairs dock levelers, racking and forklifts for distribution centers.

1. Warehousing and storage establishments (NAICS 4931) with 50 to 499 employees: Will County 33 + 31 + 8 = 72.
2. Cook County adds 20 + 12 + 11 = 43 and DuPage 9 + 13 + 3 = 25, for 140 sites.
3. Third-party logistics operators run many of them, so it assumes 140 sites map to about 90 decision-making companies.
4. At a 10% win rate in year one, that's 9 accounts and 14 sites under contract.

It targets general managers and maintenance or facilities managers at each site, and regional operations directors at the operators, and times outreach before peak season starts in August. Working out which operator runs each site, and who owns safety and maintenance there, is the research Bebop does for each account.

Subject: Dock and rack inspection before [Company]'s peak

Hi [first name],

Most damage to dock levelers and racking at sites your size happens in the last quarter, when volume and temporary staff both peak.

We inspect and repair docks, racking and forklifts across Will, Cook and DuPage counties, with a written report your insurer accepts. Could we inspect [site] in August, before peak, at no charge for the first visit?

[Your name], Prairie Dock Safety

Next step: see the metro in more detail in companies in Chicago.