Illinois

Postal abbreviation IL. 1,575 ZIP codes across 102 counties.

Population12,694,798
Postal abbreviationIL
ZIP codes1,575 ZIP codes →
Area codes217224309312331447464618630708730773779815847861872
Time zoneCentral
Counties102

Largest cities by population

Chicago · 2,711,226Aurora · 179,898Naperville · 150,692Joliet · 150,445Rockford · 147,521Elgin · 114,934Springfield · 113,330Peoria · 112,169Champaign · 89,996Waukegan · 89,076Cicero · 82,797Bloomington · 78,907Schaumburg · 76,868Evanston · 76,340Arlington Heights · 76,005Bolingbrook · 74,096Decatur · 69,815Palatine · 66,293Skokie · 66,219Des Plaines · 59,156Orland Park · 57,916Oak Lawn · 56,861Berwyn · 55,595Mount Prospect · 55,472Tinley Park · 54,842Normal · 53,569Wheaton · 53,557Oak Park · 53,292Hoffman Estates · 51,175Downers Grove · 50,054

Largest counties by population

Cook County · 5,182,090DuPage County · 930,024Lake County · 714,223Will County · 701,462Kane County · 517,255McHenry County · 312,591Winnebago County · 283,292Madison County · 264,238St. Clair County · 253,694Champaign County · 208,741

Counties in Illinois

Adams CountyAlexander CountyBond CountyBoone CountyBrown CountyBureau CountyCalhoun CountyCarroll CountyCass CountyChampaign CountyChristian CountyClark CountyClay CountyClinton CountyColes CountyCook CountyCrawford CountyCumberland CountyDe Witt CountyDeKalb CountyDouglas CountyDuPage CountyEdgar CountyEdwards CountyEffingham CountyFayette CountyFord CountyFranklin CountyFulton CountyGallatin CountyGreene CountyGrundy CountyHamilton CountyHancock CountyHardin CountyHenderson CountyHenry CountyIroquois CountyJackson CountyJasper CountyJefferson CountyJersey CountyJo Daviess CountyJohnson CountyKane CountyKankakee CountyKendall CountyKnox CountyLake CountyLaSalle CountyLawrence CountyLee CountyLivingston CountyLogan CountyMacon CountyMacoupin CountyMadison CountyMarion CountyMarshall CountyMason CountyMassac CountyMcDonough CountyMcHenry CountyMcLean CountyMenard CountyMercer CountyMonroe CountyMontgomery CountyMorgan CountyMoultrie CountyOgle CountyPeoria CountyPerry CountyPiatt CountyPike CountyPope CountyPulaski CountyPutnam CountyRandolph CountyRichland CountyRock Island CountySaline CountySangamon CountySchuyler CountyScott CountyShelby CountySt. Clair CountyStark CountyStephenson CountyTazewell CountyUnion CountyVermilion CountyWabash CountyWarren CountyWashington CountyWayne CountyWhite CountyWhiteside CountyWill CountyWilliamson CountyWinnebago CountyWoodford County

Population: U.S. Census Bureau, ACS 5-year estimates, 2024.