ZIP codes in Clayton County
24 ZIPs touch Clayton County, Iowa. The blue dashed line is the county border; orange ZIPs reach into it.
24
ZIP codes
14
cross the county line
28,537
people in these ZIPs
99
counties in IA
Most people
Clayton County ZIP list
More counties in Iowa
- Cedar County18
- Cerro Gordo County18
- Cherokee County15
- Chickasaw County10
- Clarke County9
- Clay County17
- Clinton County24
- Crawford County21
- Dallas County25
- Davis County10
- Decatur County11
- Delaware County17
Questions people actually ask
How many ZIP codes are in Clayton County, Iowa?
24 ZIP codes reach into Clayton County. 14 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Clayton County has the most people?
52162 (Postville) has about 3,744 residents, the most of any ZIP touching Clayton County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Clayton 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 Clayton 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