ZIP codes in Johnson County
12 ZIPs touch Johnson County, Illinois. The blue dashed line is the county border; orange ZIPs reach into it.
12
ZIP codes
9
cross the county line
17,222
people in these ZIPs
102
counties in IL
Most people
Johnson County ZIP list
More counties in Illinois
- Iroquois County28
- Jackson County23
- Jasper County15
- Jefferson County18
- Jersey County11
- Jo Daviess County15
- Kane County40
- Kankakee County22
- Kendall County19
- Knox County23
- LaSalle County29
- Lake County40
Questions people actually ask
How many ZIP codes are in Johnson County, Illinois?
12 ZIP codes reach into Johnson County, including 2 PO Box or single-address ZIPs placed by the town they serve. 9 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Johnson County has the most people?
62995 (Vienna) has about 6,339 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