ZIP codes in Jefferson County
17 ZIPs touch Jefferson County, Iowa. The blue dashed line is the county border; orange ZIPs reach into it.
17
ZIP codes
14
cross the county line
35,944
people in these ZIPs
99
counties in IA
Most people
Jefferson County ZIP list
More counties in Iowa
- Howard County9
- Humboldt County17
- Ida County12
- Iowa County22
- Jackson County16
- Jasper County21
- Johnson County26
- Jones County17
- Keokuk County21
- Kossuth County20
- Lee County14
- Linn County38
Questions people actually ask
How many ZIP codes are in Jefferson County, Iowa?
17 ZIP codes reach into Jefferson County, including 1 PO Box or single-address ZIPs placed by the town they serve. 14 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Jefferson County has the most people?
52641 (Mount Pleasant) has about 12,428 residents, the most of any ZIP touching Jefferson County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Jefferson 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 Jefferson 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.
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Updated 2026-11-10 · Where the data comes from