ZIP codes in St. Charles County
18 ZIPs touch St. Charles County, Missouri. The blue dashed line is the county border; orange ZIPs reach into it.
18
ZIP codes
2
cross the county line
423,022
people in these ZIPs
115
counties in MO
Most people
St. Charles County ZIP list
More counties in Missouri
- Saline County13
- Schuyler County6
- Scotland County9
- Scott County14
- Shannon County10
- Shelby County9
- St. Clair County16
- St. Francois County16
- St. Louis County56
- St. Louis city49
- Ste. Genevieve County8
- Stoddard County14
Questions people actually ask
How many ZIP codes are in St. Charles County, Missouri?
18 ZIP codes reach into St. Charles County, including 3 PO Box or single-address ZIPs placed by the town they serve. 2 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in St. Charles County has the most people?
63376 (Saint Peters) has about 74,962 residents, the most of any ZIP touching St. Charles County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in St. Charles County and another county?
Yes. ZIP codes follow mail routes, not county lines. Rows marked with a percentage show how much of that ZIP’s land is in St. Charles County. For one address, pin the exact spot on the ZIP finder to see its county.
Where does this list come from?
ZIP areas and their county overlaps come from the Census Bureau’s 2020 ZIP Code Tabulation Area to county relationship file. PO Box ZIPs have no area, so each is placed in the county of the ZIP area nearest the town it serves.
Keep exploring
Updated 2026-11-10 · Where the data comes from