ZIP codes in Union County
6 ZIPs touch Union County, Kentucky. The blue dashed line is the county border; orange ZIPs reach into it.
6
ZIP codes
5
cross the county line
15,907
people in these ZIPs
120
counties in KY
Most people
Union County ZIP list
More counties in Kentucky
- Simpson County6
- Spencer County8
- Taylor County7
- Todd County10
- Trigg County5
- Trimble County5
- Warren County11
- Washington County8
- Wayne County5
- Webster County12
- Whitley County9
- Wolfe County5
Questions people actually ask
How many ZIP codes are in Union County, Kentucky?
6 ZIP codes reach into Union County, including 1 PO Box or single-address ZIPs placed by the town they serve. 5 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Union County has the most people?
42437 (Morganfield) has about 7,064 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