Area Codes Serving Illinois
Seventeen area codes are active in Illinois today: 217, 224, 309, 312, 331, 447, 464, 618, 630, 708, 730, 773, 779, 815, 847, 861, and 872. They organize into ten numbering areas, and eight of those areas are overlay pairs where two codes share one territory. The four oldest codes, 217, 312, 618, and 815, have carried Illinois identities since 1947.
Coverage runs by region, not by city limits, so one code group can hold dozens of towns:
| Area Code | Coverage | Year Assigned | Overlay Status |
|---|---|---|---|
| 217 | Central Illinois: Springfield, Champaign-Urbana, Decatur, Quincy, Danville, Effingham | 1947 | Original code; 447 overlays it |
| 447 | Same territory as 217 | 2021 | Overlay since 2021 |
| 309 | West-central Illinois: Peoria, Bloomington-Normal, Galesburg, Macomb, Moline, Rock Island | 1957 | Split from 815/217 territory; 861 overlays it |
| 861 | Same territory as 309 | 2023 | Overlay since February 24, 2023 |
| 312 | Central Chicago, concentrated in the Loop | 1947 | Original code; 872 overlays it |
| 773 | Most Chicago neighborhoods outside the central area | 1996 | Split from 312; 872 overlays it |
| 872 | Citywide Chicago overlay across 312 and 773 | 2009 | Overlay since 2009 |
| 708 / 464 | South and west Chicago suburbs, western and southern Cook plus parts of Will County | 1989 / 2022 | 464 overlay since January 21, 2022 |
| 630 / 331 | Western suburbs: DuPage County, parts of Kane, Naperville, Wheaton, Aurora | 1996 / 2007 | 331 overlay since 2007 |
| 847 / 224 | North and northwest suburbs: Lake County, northern Cook, Evanston, Waukegan, Schaumburg, Elgin area | 1996 / 2002 | 224 overlay since 2002 |
| 815 / 779 | Northern Illinois outside the Chicago core: Rockford, DeKalb, Joliet area, LaSalle, Kankakee | 1947 / 2007 | 779 overlay since 2007 |
| 618 / 730 | Southern Illinois and Metro East: Alton, Belleville, Carbondale, East St. Louis, Edwardsville, Marion | 1947 / 2023 | 730 overlay after July 7, 2023 |
The Illinois Commerce Commission is the state's regulator for these assignments. Its area-code hub gathers the Illinois press releases, ICC orders, and NANPA links behind every code on the table.
When a new overlay is announced, this is where the official Illinois notice appears first, ahead of most news coverage.
Which Illinois Region Uses Which Code
Chicago works differently from the rest of the state, so it helps to read the map in two halves. Inside the city, 312 holds the Loop and central neighborhoods, 773 covers most everything else, and 872 floats over both. The suburbs then form a ring of code pairs around the city, with the pair you get depending on the direction you head out of town.
- Chicago proper - 312 downtown, 773 in the neighborhoods, 872 overlaying the whole city
- South and west suburbs - 708 and 464, covering much of western and southern Cook County into Will County
- Western suburbs - 630 and 331 across DuPage and parts of Kane County
- North and northwest suburbs - 847 and 224 through Lake County, northern Cook, and parts of McHenry and Kane
- Northern Illinois - 815 and 779 from Rockford through DeKalb, the Joliet area, and Kankakee
- Central and southern Illinois - 217/447 around Springfield and Champaign, 309/861 around Peoria and the Quad Cities, 618/730 across the south and Metro East
The codes carry identity as well as geography. A 312 number still signals central Chicago, and 773 reads as the neighborhoods. The 708 code keeps its south-and-west suburban feel even with 464 layered on. Downstate, 217 means Springfield and Champaign country, 618 means southern Illinois and Metro East, and the wide 815 band takes in both Rockford and the Joliet area. The overlay codes inherit those identities slowly, which is why an 872 or 447 number can read as unfamiliar even when it is local.
NANPA, the national numbering administrator, draws the authoritative maps. Its area-code map page serves a state map for Illinois alongside its area-code search.
The map settles boundary questions fast, like which side of a county line flips from 815 to 309 territory.
Overlay vs Split: How Illinois Got Here
Illinois has used both relief methods, and the state's timeline shows the industry changing its mind. Every change before 2000 was a split: 773 broke away from 312, and 630 with 847 broke away from 708, each time handing thousands of customers new numbers. Every change since has been an overlay, which adds a code to the same ground and lets everyone keep what they have. The trade-off is that overlays force full-number dialing, because two homes on one block can share the same seven digits under different codes.
- Overlay
- A new code added over the same geography. Existing numbers stay put. All eight of Illinois's post-2000 codes arrived this way.
- Split
- The territory divides, and one part moves to a new code with new numbers. Illinois's splits came in 1957, 1989, and 1996.
- Permissive Dialing
- A transition window when the old dialing pattern still connects before the new one becomes mandatory on a set date.
Dialing Rules Across Illinois
There is no single Illinois dialing rule. NANPA's 2025 annual report splits the state's code groups into two camps. The 217/447, 309/861, and 618/730 regions use 10-digit local dialing: area code plus number. The 224/847, 312/773/872, 331/630, 464/708, and 779/815 regions use 1+10-digit local dialing, with the 1 in front even for a call across the street. Three regions changed for a reason beyond overlays: 309, 618, and 708 moved to mandatory 10-digit dialing by October 24, 2021 so the 988 crisis line could work as a three-digit code.
Each transition ran through a permissive period first. In the 217 region, for example, both dialing patterns connected until mandatory 10-digit dialing took hold on February 27, 2021, ahead of the 447 overlay later that year. Those grace windows have all closed.
Important: Seven-digit local calls no longer connect anywhere in Illinois; save every contact with its full area code, and add the 1 in the Chicago-area code groups.
Area codes are only one kind of code an Illinois caller deals with. The N11 shortcuts, star codes, and toll-free prefixes sit with the rest of the Illinois phone codes.
Illinois Area Code Timeline
The sequence reads like a growth chart for the state's phone demand. Four broad codes handled everything in 1947. Chicago's rise, then fax machines, modems, and cell phones, kept forcing new relief, and the pace picked up sharply in the 2020s. Each change followed the same pressure: a region's supply of unassigned numbers ran low, and either a split or an overlay restored it.
| Year | Event |
|---|---|
| 1947 | Illinois assigned original codes 217, 312, 618, and 815 |
| 1954 | 217 and 618 boundary adjusted |
| 1957 | 309 split off for west-central Illinois |
| 1989 | 708 split from 312, taking the Chicago suburbs |
| 1996 | 773 split from 312; 630 and 847 split from 708 |
| 2002 | 224 overlaid 847 |
| 2007 | 331 overlaid 630; 779 overlaid 815 |
| 2009 | 872 overlaid Chicago's 312 and 773 |
| 2021 | 447 overlaid 217; 10-digit dialing mandatory in 217 from February 27; 309, 618, and 708 went 10-digit by October 24 for the 988 transition |
| 2022 | 464 numbers became available in the 708 region on January 21 |
| 2023 | 861 available in the 309 region from February 24; 730 available in the 618 region after July 7 |
Note: the 1996 double split marked the last time Illinois residents had to change their own numbers; every code since has been an overlay.
Prefixes Under the Illinois Area Codes
The three digits after the area code, the NXX or central-office code, narrow a number down further. Prefixes map to rate centers, the billing zones beneath each area code, and some Illinois prefixes are recognizable on sight. State government numbers around Springfield cluster in 217-782 and 217-785. Chicago city government uses 312-744, Cook County uses 312-603, and Chicago Public Schools numbers start with 773-553. Those patterns help identify an official caller, though portability means a prefix alone never proves who holds a number now. The prefix-level detail, including NANPA's assignment records, lives with the exchange material on the phone codes page.
Future Area Code Relief for Illinois
Nothing new is on the board right now. Official NANPA and ICC sources list no additional Illinois area code beyond the overlays already implemented. The recent ones bought years of number supply: 447, 464, 861, and 730 all arrived between 2021 and 2023 and are still filling.
When relief does become necessary, the process is public. NANPA forecasts when each numbering area will run out, convenes the industry, and files a plan that the Illinois Commerce Commission must approve before any new code goes live. The NANPA relief-planning page explains that cycle, from exhaust forecasting through planning letters and relief reports.
For residents, a future overlay would mean nothing more than new numbers appearing under an extra code. Existing Illinois numbers would not change.
Verifying an Illinois Area Code
Scam callers lean on unfamiliar codes, so a quick verification is worth the minute it takes. Check the code against NANPA's map or search to confirm it exists and belongs where the caller claims. Cross-check Illinois-specific announcements at the ICC, which is useful for the newer codes like 447, 464, 730, and 861 that still surprise people. The FCC's consumer guide covers why 10-digit dialing became standard, including the 988-driven changes.