ZIP codes in Johnson County
26 ZIPs touch Johnson County, Iowa. The blue dashed line is the county border; orange ZIPs reach into it.
26
ZIP codes
16
cross the county line
230,784
people in these ZIPs
99
counties in IA
Most people
Johnson County ZIP list
More counties in Iowa
- Humboldt County17
- Ida County12
- Iowa County22
- Jackson County16
- Jasper County21
- Jefferson County17
- Jones County17
- Keokuk County21
- Kossuth County20
- Lee County14
- Linn County38
- Louisa County13
Questions people actually ask
How many ZIP codes are in Johnson County, Iowa?
26 ZIP codes reach into Johnson County, including 2 PO Box or single-address ZIPs placed by the town they serve. 16 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Johnson County has the most people?
52404 (Cedar Rapids) has about 42,958 residents, the most of any ZIP touching Johnson County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Johnson 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 Johnson 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