North American Numbers Source-cited · ownership disclosed
Area code
872
In service
United States · since 2009

Chicago (Citywide Overlay)

Area code 872 is an all-services overlay that commenced service on November 7, 2009, covering the entire city of Chicago by overlaying both 312 and 773.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
Chicago (Citywide Overlay)
Type
geographic
Status
in service
In service since
2009
Projected exhaust
2049 Q1

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 872 is

All of the city of Chicago - the combined geography of 312 (downtown) and 773 (outer neighborhoods).

Communities served wholly or partly by 872:

Chicago (citywide)

Not a distinct geography of its own; shares the exact footprint of 312 + 773.

B · Relationships

How it relates to other codes

The codes 872 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Overlay · 2009 312 Chicago (The Loop / Downtown) Overlays 312 (downtown Chicago).
Overlay · 2009 773 Chicago (Outer Neighborhoods) Overlays 773 (outer Chicago neighborhoods).
What's changing. All-services overlay of the combined 312 + 773 area (all of Chicago), in service since Nov 7, 2009.
C · History

How 872 got here

2007-08-10
Illinois Commerce Commission announced 872 would overlay 312 and 773.
Source: Wikipedia - Area code 872
2009-11-07
872 commenced service; the third overlay serving Chicago; full 10-digit dialing required.
Source: Wikipedia - Area code 872
D · Capacity

How full it is

Prefixes assigned
290
Prefixes available
510
Thousands-blocks assigned
2,649

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 872 with another code →
Sources
Wikipedia ↗
Area code 872
Illinois Commerce Commission ↗
Chronological History of Area Code Relief in Illinois
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.