ZIP codes in Knox County

23 ZIPs touch Knox County, Illinois. The blue dashed line is the county border; orange ZIPs reach into it.

ZIP codes

cross the county line

60,160

people in these ZIPs

102

counties in IL

Most people

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Knox County ZIP list

More counties in Illinois

All 102 counties in Illinois

Questions people actually ask

How many ZIP codes are in Knox County, Illinois?

23 ZIP codes reach into Knox County. 12 of them are only partly in the county and also cover a neighboring county.

Which ZIP code in Knox County has the most people?

61401 (Galesburg) has about 30,580 residents, the most of any ZIP touching Knox County, in the Census Bureau’s ACS 2020–2024 estimates.

Can a ZIP code be in Knox 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 Knox 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