312 Area Code

The 312 area code is found in the state of Illinois, and spans 7 different Counties. Listed below are the 7 Counties that reside inside of the 312 area code. Included under the Counties are the cities within the given County.
Champaign County Illinois
Cook County Illinois
Arlington Heights, Blue Island, Brookfield, Chicago, Cicero, Country Club Hills, Des Plaines, Elmwood Park, Evanston, Glenview, Harwood Heights, Northbrook, Oak Lawn, Oak Park, Park Ridge, Prospect Heights, Rolling Meadows, Schaumburg, Western Springs, Wheeling
Dupage County Illinois
Bensenville, Clarendon Hills, Darien, Hinsdale, Lombard, Medinah, Oak Brook, Villa Park, Willowbrook
Kane County Illinois
Lake County Illinois
Barrington, Buffalo Grove, Deerfield, Lake Zurich, Lincolnshire
Mchenry County Illinois
Algonquin, Crystal Lake
Will County Illinois