Area Code 312

312 area code is being used for dialing/telecommunication purposes in Illinois, covering only one major city and 2 counties, according to (NANP) North American Numbering Plan for 3-digit Numbering Plan Area (NPA) code. All the areas using NPA code 312 is part of CST (Central Standard Time) timezone.

312 Area Code Covers only one City

Check this below table to know only one major city (having more than 20,000 population) in Illinois using numbering plan area code 312 for dialing/telecommunication purposes.

City	ZIP Codes	Population
Chicago, IL	61	2,721,914

2 Counties Using 312 as Area Code

312 area code is being used in 2 counties of Illinois for dialing/telecommunication purposes.

• Cook County, IL
• DuPage County, IL

43 More NPA Codes Related to Area Code 312

1 or more of these 43 NPA codes are being used in the same or adjacent states of Illinois in the United States.

• 217 Area Code
• 219 Area Code
• 224 Area Code
• 260 Area Code
• 262 Area Code
• 270 Area Code
• 309 Area Code
• 314 Area Code
• 317 Area Code
• 319 Area Code
• 331 Area Code
• 364 Area Code
• 414 Area Code
• 417 Area Code
• 463 Area Code
• 502 Area Code
• 515 Area Code
• 534 Area Code
• 563 Area Code
• 573 Area Code
• 574 Area Code
• 606 Area Code
• 608 Area Code
• 618 Area Code
• 630 Area Code
• 636 Area Code
• 641 Area Code
• 660 Area Code
• 708 Area Code
• 712 Area Code
• 715 Area Code
• 765 Area Code
• 773 Area Code
• 779 Area Code
• 785 Area Code
• 812 Area Code
• 815 Area Code
• 816 Area Code
• 847 Area Code
• 859 Area Code
• 872 Area Code
• 920 Area Code
• 930 Area Code

Only One State Uses Area Code 312

• Illinois