Area Code 636
Missouri
Area code 636 serves Missouri, primarily O'Fallon, in the Central Time (CT) time zone. It was created from a split of area code 314.
Split Area Code
This area code was created by splitting an existing area code into separate geographic regions. When a split occurs, some customers in the original area code region are assigned the new area code.
This area code was split from area code 314 (St. Louis).
In service since: 22-May-1999
Demographics
The estimated population served by area code 636 is approximately 1,330,725. The population density is 222 people per square mile, which is higher than the national average of 94. The median household income is $81,340, which is near the national median of $78,538. Approximately 33.2% of adults hold a bachelor's degree or higher, compared to the national rate of 35.0%. This rate is near the national average. The poverty rate stands at 8.2%, which is lower than the national rate of 12.4%.
History
Area code 636 was created from a split of area code 314. It was introduced in 1999 as part of a geographic division to provide additional numbering resources.
Geographic Coverage
Area code 636 serves Missouri, primarily the O'Fallon area, in the Central Time (CT). It covers 86 communities. The geographic center of this area code is approximately 38.60°N, 90.71°W.
Demographics & Economics
- Total Population
- 1,330,725
- Population Density
- 222 people/sq miabove U.S. average (U.S.: 94 people/sq mi)
- Median Household Income
- $81,340near U.S. median (U.S.: $78,538)
- Poverty Rate
- 8.2%below U.S. average (U.S.: 12.4%)
- Unemployment Rate
- 3.6%below U.S. average (U.S.: 5.2%)
- Education Attainment
- Bachelor's Degree+33.2%near U.S. average (U.S.: 35.0%)High School or Lower30.2%
Statistics are population-weighted aggregations from Census ACS 5-year estimates.See Sources for details.
Geographic Coverage
State
MO
Major Cities
- O'Fallon
- St. Charles
- St. Peters
- Chesterfield
- Wentzville
- Wildwood
- Ballwin
- Hazelwood
- Arnold
- Manchester
- Lake St. Louis
- Washington
- Troy
- Dardenne Prairie
- Festus
- Union
- Eureka
- Town and Country
- Ellisville
- Sunset Hills
- Warrenton
- Murphy
- Pacific
- Valley Park
and 62 more cities
Time Zone
- Central Time (CT)
Current Time
County Coverage
Population-weighted county share based on aggregated ZCTA population (100% = total mapped population for area code 636).
| County | Population | Share |
|---|---|---|
| St. Charles, MO | 418,481 | 31.4% |
| Jefferson, MO | 283,401 | 21.3% |
| St. Louis, MO | 275,695 | 20.7% |
| Franklin, MO | 106,743 | 8.0% |
| Lincoln, MO | 89,263 | 6.7% |
| St. Francois, MO | 52,729 | 4.0% |
| Warren, MO | 48,820 | 3.7% |
| Ste. Genevieve, MO | 27,913 | 2.1% |
| Washington, MO | 24,869 | 1.9% |
| Montgomery, MO | 2,811 | 0.2% |
Call Context
This area code covers multiple cities and communities across a broad region in Missouri. It was created as a geographic split from area code 314, dividing the original territory into separate numbering regions.
Nearby Area Codes
Area codes geographically closest to 636.
Other Area Codes in Missouri
Area codes that also serve Missouri, linked for easy comparison.
Frequently Asked Questions
Common questions about area code 636 and how phone numbering works.
Phone numbers are assigned based on where the number was originally provisioned, not the caller's current location. Mobile phones retain their number when users move, and businesses may use numbers from regions where they don't have a physical presence. VoIP services can also provision numbers from virtually any area code.
Yes, mobile phones can have numbers from any area code in the region they were activated. Wireless carriers assign numbers from available pools regardless of phone type. When users change carriers or move to new areas, they typically keep their original number, which may have a different area code than their current location.
Start by looking up the area code on this site to understand its general geographic region. For the specific number, options include using your carrier's caller ID features or checking public directories. If you suspect fraud, you can report it to the FTC. To file a complaint about robocalls or spoofed numbers, visit the FCC Consumer Complaint Center. You can also register your number with the National Do Not Call Registry to reduce unwanted calls. Keep in mind that caller ID can display any name the caller chooses to set.
Area codes are sometimes "split" when an existing code runs out of available number combinations. In a split, the original territory is divided geographically, with each portion receiving its own area code. This area code was split from area code 314. See our guide on splits and overlays for details.
While Washington is a prominent city in this area code's coverage, the code serves the broader surrounding region as well. Area codes are assigned geographically and typically cover multiple cities, towns, and communities beyond any single anchor city.
The estimated total population served by area code 636 is based on aggregated U.S. Census Bureau data for the counties within this area code. The population varies significantly between dense urban codes serving millions and rural codes covering smaller populations. You can find the specific population figure in the demographics section above.