ZIP codes in Union County

22 ZIPs touch Union County, Ohio. The blue dashed line is the county border; orange ZIPs reach into it.

ZIP codes

cross the county line

289,244

people in these ZIPs

counties in OH

Most people

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Union County ZIP list

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Questions people actually ask

How many ZIP codes are in Union County, Ohio?

22 ZIP codes reach into Union County, including 1 PO Box or single-address ZIPs placed by the town they serve. 18 of them are only partly in the county and also cover a neighboring county.

Which ZIP code in Union County has the most people?

43015 (Delaware) has about 61,401 residents, the most of any ZIP touching Union County, in the Census Bureau’s ACS 2020–2024 estimates.

Can a ZIP code be in Union 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 Union 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