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County ZIP codes · Missouri · FIPS 29183

St. Charles County, MO ZIP Codes

St. Charles County, Missouri has 18 ZIP codes (Census 2020 ZCTA-county file; GeoNames postal codes, October 2026): 15 residential and 3 for PO boxes or a single organization. 14 of the residential ones lie mainly in St. Charles County and 1 mainly in a neighboring county; 2 cross the county line. Median household income ranges from $85,308 in 63301 (Saint Charles) to $170,598 in 63341 (Defiance) (Census Bureau, ACS 2020-2024).

  • ACS2020-24
  • Census2020

Where are the ZIP codes of St. Charles County?

63301 · Saint Charles: $85k63303 · Saint Charles: $99k63304 · Saint Charles: $114k63332 · Augusta: $146k63341 · Defiance: $171k63348 · Foristell: $116k63357 · Marthasville: $92k63365 · New Melle: $54k63366 · O Fallon: $101k63367 · Lake Saint Louis: $138k63368 · O Fallon: $124k63373 · Portage Des Sioux: $89k63376 · Saint Peters: $96k63385 · Wentzville: $112k63386 · West Alton: $110k633576330163385633666334863332633046338663341633766330363373633686336763301 · Saint Charles: $85k63303 · Saint Charles: $99k63304 · Saint Charles: $114k63332 · Augusta: $146k63341 · Defiance: $171k63348 · Foristell: $116k63357 · Marthasville: $92k63365 · New Melle: $54k63366 · O Fallon: $101k63367 · Lake Saint Louis: $138k63368 · O Fallon: $124k63373 · Portage Des Sioux: $89k63376 · Saint Peters: $96k63385 · Wentzville: $112k63386 · West Alton: $110k6335763301633856336663348633326330463386633416337663303633736336863301 · Saint Charles: $85k63303 · Saint Charles: $99k63304 · Saint Charles: $114k63332 · Augusta: $146k63341 · Defiance: $171k63348 · Foristell: $116k63357 · Marthasville: $92k63365 · New Melle: $54k63366 · O Fallon: $101k63367 · Lake Saint Louis: $138k63368 · O Fallon: $124k63373 · Portage Des Sioux: $89k63376 · Saint Peters: $96k63385 · Wentzville: $112k63386 · West Alton: $110k63357633016338563366633326330463386
The residential ZIP codes of St. Charles County (whole outlines, including the parts in neighboring counties), shaded by median household income in national fifths (ACS 2020-2024). <$54.1k$98.1k+no figure

Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).

How different are its ZIP codes?

The middle half of its ranked ZIP codes (1,000+ people living in households) report median household incomes between $96,393 and $115,661.

They carry 12 postal town names.

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013).

All 15 residential ZIP codes in St. Charles County

14 ZIP codes lie mainly in St. Charles County; 1 more reaches into it from a neighboring county and follows the first table.

Residential ZIP codes mainly in St. Charles County, largest first; "In this county" is the share of the ZIP's land in the county
In this county
63376 Saint Peters 74,962 1,868 $96k $275k 100%
63366 O Fallon 54,769 790 $101k $305k 100%
63301 Saint Charles 52,667 625 $85k $268k 100%
63385 Wentzville 51,330 768 $112k $347k 100%
63368 O Fallon 46,966 2,896 $124k $349k 100%
63303 Saint Charles 46,089 2,333 $99k $321k 100%
63304 Saint Charles 43,195 784 $114k $351k 100%
63367 Lake Saint Louis 29,725 2,295 $138k $409k 100%
63348 Foristell 10,394 186 $116k $386k 78%
63341 Defiance 3,515 91 $171k $607k 100%
63332 Augusta 1,651 29 $146k $385k 100%
63373 Portage Des Sioux 690 37 $89k $221k 100%
63386 West Alton 482 15 $110k $157k 100%
63365 New Melle 51 155 $54k – 100%

Partly in St. Charles County

Residential ZIP codes mainly in another county that reach at least 1% into St. Charles County, by their share here
In this county
63357 Marthasville 6,536 53 $92k $293k 4%

Download the 18 ZIP codes as CSV

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; county shares by land area (Census 2020 ZCTA-county relationship file).

Which ZIP codes cross the county line?

2 ZIP codes of St. Charles County extend into another county. A ZIP code follows mail routes, not county borders.

Share of each ZIP code's land in St. Charles County and in the neighboring counties
ZIPIn St. CharlesElsewhere
6334878%Warren County 19%; Lincoln County 2%
633574%Warren County 96%

Source: U.S. Census Bureau, 2020 ZCTA-county relationship file (shares of land area).

PO Box and single-organization ZIP codes

ZIP codes in St. Charles County without a residential area (GeoNames postal codes)
ZIPPostal name
63302Saint Charles
63338Cottleville
63346Flinthill

Source: GeoNames postal codes (CC BY 4.0).

Which first three digits do St. Charles County's ZIP codes use?

The first three digits of a ZIP code name the sectional center, the mail processing plant that sorts it. Every ZIP code of St. Charles County starts with 633.

Three-digit prefixes of St. Charles County's ZIP codes, the sectional center for each (USPS labeling list L005, effective October 1, 2026) and how many of the prefix's codes are St. Charles County's
PrefixSectional centerHereAll codes
633 St Louis, MO (SCF 630) 18 51

Source: U.S. Postal Service, labeling list L005 (3-digit ZIP Code prefix groups, SCF sortation), effective October 1, 2026.