ZIP codes in Knox County
20 ZIPs touch Knox County, Maine. The blue dashed line is the county border; orange ZIPs reach into it.
20
ZIP codes
0
cross the county line
41,003
people in these ZIPs
16
counties in ME
Most people
Knox County ZIP list
More counties in Maine
- Androscoggin County23
- Aroostook County47
- Cumberland County52
- Franklin County21
- Hancock County45
- Kennebec County35
- Lincoln County28
- Oxford County36
- Penobscot County49
- Piscataquis County16
- Sagadahoc County9
- Somerset County26
Questions people actually ask
How many ZIP codes are in Knox County, Maine?
20 ZIP codes reach into Knox County, including 1 PO Box or single-address ZIPs placed by the town they serve. Every ZIP area here lies wholly inside the county.
Which ZIP code in Knox County has the most people?
04841 (Rockland) has about 7,035 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