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City ZIP codes · Missouri

O Fallon, MO ZIP Codes

2 ZIP codes use the postal name O Fallon, Missouri (Census 2020 ZCTAs and GeoNames postal codes, October 2026), all residential. Median household income runs from $100,621 in 63366 to $124,297 in 63368, 1.2 times as much (Census Bureau, ACS 2020-2024). O Fallon's most populous ZIP code is 63366, with 54,769 people (ACS 2020-2024); 0% of its land is in the city of O Fallon.

  • ACS2020-24
  • Census2020
  • GeoNames2026

Where are O Fallon's ZIP codes?

63366: $101k median household income63368: $124k median household income633666336863366: $101k median household income63368: $124k median household income633666336863366: $101k median household income63368: $124k median household income6336663368
The 2 residential ZIP codes named O Fallon, shaded by median household income in national fifths (ACS 2020-2024). Select a ZIP to open it. <$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 O Fallon's ZIP codes?

The highest median household income is in 63368 ($124,297), the lowest in 63366 ($100,621). Home values run from $304,500 in 63366 to $349,200 in 63368.

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates (B19013, B25077, B01003).

All 2 residential ZIP codes of O Fallon

Residential ZIP codes with the postal name O Fallon, MO, largest first (ACS 2020-2024); sort by any column
County
63366 St. Charles County 54,769 790 $101k $305k
63368 St. Charles County 46,966 2,896 $124k $349k

Download the 2 ZIP codes as CSV

Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; 2023 Gazetteer land areas (2020 ZCTAs); town names from simplemaps US ZIP Codes (CC BY 4.0) and GeoNames (CC BY 4.0).

Which counties do O Fallon's ZIP codes reach?

O Fallon's residential ZIP codes lie in St. Charles County.

Which places do O Fallon's ZIP codes cover?

A postal name is not a city limit. By the Census Bureau's places, O Fallon's residential ZIP codes cover 3 other places, each listed with the ZIP codes that have at least 5% of their land in it or hold most of the place:

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

Which first three digits do O Fallon'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 O Fallon starts with 633.

Three-digit prefixes of O Fallon'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 O Fallon's
PrefixSectional centerHereAll codes
633 St Louis, MO (SCF 630) 2 51

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