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

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.

Updated 2026-11-10 · Where the data comes from