Illinois Area Codes

Area codes: 17
ZIP codes: 1,575
Cities & towns: 1,286
Counties: 102

Every area code in Illinois

All Illinois area codes, what each primarily serves, and which share ground with another.
Area code	Primarily serves	Shares ground with	In service
217	Springfield	447	1947
224	Chicago	847	2002
309	Peoria	861	1957
312	Chicago	872	1947
331	Chicago	630	2007
447	Springfield	217	2021
464	Chicago	708	2022
618	Belleville	730	1947
630	Chicago	331	1996
708	Chicago	464	1989
730	Belleville	618	2023
773	Chicago	872	1996
779	Joliet	815	2007
815	Joliet	779	1947
847	Chicago	224	1996
861	Peoria	309	2023
872	Chicago	312, 773	2009

A code in the “shares ground” column is an overlay: it covers the same territory rather than a different part of Illinois, which is why local calls there are dialled as ten digits.

Which codes share the same ground

Illinois has 8 groups of codes that overlay one another: the codes inside a group cover the same territory rather than different parts of the state, so local calls there are dialled as ten digits.

Where Illinois's communities sit

Each point is an Illinois community, plotted from its record coordinates. The outline is the convex envelope of those points — a footprint, not a boundary.

Reference points and footprint
Not an official NANPA boundary
Not a USPS delivery area

Largest Illinois cities and their codes

largest 25

Scope every area code assigned to Illinois. Source LocalCallingGuide NPA list (2026-07 NPA list) and geoinfo-dataset (full_dataset) ZIP→NPA (2018 snapshot). Updated 16 July 2026. Overlay relationships come from the numbering-plan authority; the city match is computed.