About Area Code 636
- Region Code
- 636
- City
- St Charles
- State
- Missouri
- Population
- 772,215
- Largest City
- O'Fallon
- Time Zone
- Central Time
Missouri
(636) Area Code 636 — St Charles, Missouri
636 Area Code – St Charles, Missouri: Location, Time Zone & History
Build trust, look local, and grow your business with a phone number in area code 636. Instant activation, flexible forwarding, and clear pricing.
Map of Area Code 636
Available Phone Numbers
Choose from popular and easy-to-remember local numbers. Instant purchase and activation.
History & Cultural Notes
St. Charles County anchors area code 636, one of the fastest-growing parts of Missouri and the historic starting point of the Lewis and Clark Expedition in 1804, an event still commemorated at Frontier Park in historic St. Charles.
The numbering area split from 314 effective May 22, 1999, taking in the outer western St. Louis suburbs -- St. Charles, Jefferson, Warren, and most of Franklin County, along with portions of St. Louis, Lincoln, and Montgomery counties -- while the City of St. Louis and its inner-ring suburbs kept 314. That split followed an earlier 1996 division that had sent central and southeastern Missouri into area code 573; growth from cellphones, pagers, and fax machines pushed 314 back toward exhaustion within just a couple of years, setting up the 636 split. Unlike neighboring 314, which gained the overlay code 557 in 2022, 636 remains a single, non-overlaid area code with no relief currently planned.
- Automotive manufacturing at the General Motors Wentzville Assembly plant, operating since 1980 and one of the region's largest employers
- Aerospace and defense work tied to Boeing
- Financial services and technology operations for Citi and Mastercard in St. Charles County
- Logistics, distribution, and healthcare
Beyond St. Charles, the area also serves O'Fallon, St. Peters, Chesterfield, and Wentzville.