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zipcodes.pro — AREA-CODE/636

636 area code

Area code 636 is in Missouri. It covers O Fallon, St. Charles, St. Peters and 89 other places: 70 ZIP codes in St. Charles, St. Louis, Jefferson and 5 other counties. Local time there is , Central Time. In service since 1999, with no overlay.

Time zone
Central
Largest city
Saint Charles
Overlays
none
In service since
1999
Rate centres
46
Prefixes assigned
435 (4,350,000 numbers)

Who calls from a 636 number

NANPA records the carrier each block of 636 numbers is assigned to. Of the 4.0 million 636 numbers assigned, 47% are with cable, internet-calling, business and other carriers (Onvoy and Verizon Business); 27% with mobile carriers (AT&T Mobility and T-Mobile); 25% with local phone companies (AT&T and Brightspeed).

That is who the numbers were assigned to: people keep their number when they change carrier, so any one number may have moved since.

Carriers holding the most 636 numbers
CarrierKindShare
AT&TLandline19%
OnvoyCable, VoIP, other17%
AT&T MobilityMobile12%
T-MobileMobile10%
BrightspeedLandline6%
Verizon BusinessCable, VoIP, other5%

An area code says where a number was issued, not where the caller is: people keep their numbers when they move, and caller ID can be set to show any number, which the FCC calls spoofing. If a call you did not expect asks for money or personal details, the FCC advises hanging up and calling the company back on a number you look up yourself. Unwanted calls can be reported to the FTC at ReportFraud.ftc.gov.

Places in area code 636

The 37 places with a telephone rate centre of their own using 636, largest first. Each links to its ZIP codes.

Places in area code 636
PlaceZIP codesPopulation
O Fallon, MO 2 93,801
St. Charles, MO 4 71,508
St. Peters, MO 1 59,092
Chesterfield, MO 3 49,574
Wentzville, MO 1 47,061
Manchester, MO — 18,160
Washington, MO 1 15,130
Troy, MO 1 13,947
Dardenne Prairie, MO — 13,503
Eureka, MO 1 13,081
Union, MO 1 12,781
Warrenton, MO 1 9,066
Pacific, MO 1 7,475
Valley Park, MO 1 6,795
De Soto, MO 1 6,470
Imperial, MO 1 5,488
Wright City, MO 1 5,240
St. Clair, MO 1 4,789
Fenton, MO 2 4,088
Moscow Mills, MO 1 3,823
High Ridge, MO 1 3,714
Defiance, MO 1 3,515
Hillsboro, MO 1 3,500
Gray Summit, MO 1 2,991
Marthasville, MO 1 2,328
Winfield, MO 1 1,745
Cedar Hill, MO 1 1,261
Foristell, MO 1 1,096
Jonesburg, MO 1 806
Hawk Point, MO 1 736
New Melle, MO 1 452
Portland, MO 1 299
Augusta, MO 1 285
High Hill, MO 1 238
Old Monroe, MO 1 236
Foley, MO 1 140
Truxton, MO 1 28

Nearby places using 636

These places have no rate centre of their own in NANPA's records; the nearest one uses 636. Near an area-code boundary that can be wrong for part of a town.

ZIP codes in area code 636

70 ZIP codes in 60 towns, by the town each is mailed to, largest first. Each links to its own page.

Where 636 numbers are issued

NANPA's rate centres with the most 636 prefixes (each prefix is 10,000 numbers), under NANPA's own abbreviated names.

Rate centres using area code 636
Rate centrePlacePrefixes
ST CHARLES Saint Charles 44
CHESTERFLD Chesterfield 36
HARVESTER — 36
MANCHESTER Manchester 27
OFALLON O Fallon 24
FENTON Fenton 16

Counties

The counties of its ZIP codes, most residents first, with how many of its ZIP codes each has.

Which code covers where you are now? What area code am I in? answers from your location.

Questions about area code 636

Where is area code 636?

Area code 636 is in Missouri. It covers O Fallon, St. Charles, St. Peters and 89 other places: 70 ZIP codes in St. Charles, St. Louis, Jefferson and 5 other counties.

What ZIP codes are in area code 636?

70 ZIP codes, by the town each is mailed to: O Fallon (2, 63366 to 63368), St. Charles (4, 63301 to 63304), St. Peters (63376), Chesterfield (3, 63005 to 63017) and 56 more towns. The full list is on this page.

What time zone is area code 636 in?

Central time.

Is a 636 number a mobile or a landline?

It can be either. 27% of 636 numbers are assigned to mobile carriers and 25% to local phone companies (NANPA, 2026-10-10); the rest are with cable, internet-calling, business and paging carriers. A number keeps its area code when it moves to another carrier.

Does a 636 number mean the caller is in Missouri?

Not necessarily. An area code says where the number was first issued. People keep their numbers when they move or switch carriers, and calling software can show any number, so a 636 call can come from anywhere.

Other area codes in Missouri

All 9 Missouri area codes, by area, with the cities each covers

Source: NANPA NPA database, central office code and thousands-block assignments, 2026-10-10. Places are matched to NANPA's rate centres by name; see sources.

Cite this page

zipcodes.pro. “Area code 636.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/area-code/636

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