The main cities in Illinois are:
Chicago (773/312/872), Joilet (779/815), Naperville (331/630), Rockford (779/815) and Elgin (847/224).
The main airport in Illinois is the Chicago O'Hare International Airport.
The main WhatsApp businesses are Accommodation and Food Services, Retail Trade and Transportation and Warehousing. You can contact all these types of businesses with WhatsApp.