North American Numbers Source-cited · ownership disclosed
Area code
636
In service
United States · since 1999

St. Charles / western St. Louis suburbs

Created in 1999 from a split of 314, area code 636 serves the western and outer suburbs of the St. Louis metropolitan area. It has no overlay.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
St. Charles / western St. Louis suburbs
Type
geographic
Status
in service
In service since
1999
Projected exhaust
2075 Q3

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 636 is

East-central Missouri: St. Charles, Jefferson, Warren, Franklin counties and parts of St. Louis, Lincoln, and Montgomery counties..

Communities served wholly or partly by 636:

St. CharlesSt. PetersO'FallonWentzvilleChesterfieldBallwinArnoldWashingtonUnionWildwood
B · Relationships

How it relates to other codes

The codes 636 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?

Split from · 1999 314 St. Louis 636 split from 314, taking the outer/western St. Louis suburbs.
Related · 1996 573 Columbia / Jefferson City / eastern Missouri Adjacent to the south and west.
What's changing. No overlay; 636 is the sole area code for its territory.
C · History

How 636 got here

1999-05-22
Created by geographic split of 314 as the St. Louis suburbs neared exhaustion.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
456
Prefixes available
344
Thousands-blocks assigned
2,466

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

Compare 636 with another code →
Sources
Wikipedia ↗
Area code 636
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.