ZIP codes in Mercer County

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

ZIP codes

cross the county line

32,544

people in these ZIPs

102

counties in IL

Most people

← All Illinois ZIP codes

Mercer County ZIP list

More counties in Illinois

All 102 counties in Illinois

Questions people actually ask

How many ZIP codes are in Mercer County, Illinois?

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

Which ZIP code in Mercer County has the most people?

61264 (Milan) has about 10,073 residents, the most of any ZIP touching Mercer County, in the Census Bureau’s ACS 2020–2024 estimates.

Can a ZIP code be in Mercer 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 Mercer 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.

Keep exploring

My ZIP codeYour ZIP, lit up on the map, with the numbers behind it.Open What county am I inYour county, lit up with its border and how far the county line is.Open What time zone am I inYour zone, UTC offset and daylight saving, plus every US zone at a glance.Open ZIP code mapEvery US ZIP code with its boundary. Hover, tap, color by data.Open Radius mapDrag a circle and watch every ZIP inside light up. Copy or export.Open ZIP GuessrFive ZIPs a day. Tap where each one is, keep your streak, share your score.Open ZIP codes near meEvery ZIP around you, nearest first, with distance and direction.Open ZIP distanceMiles between two ZIP codes, drawn as a flight path.Open

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