ZIP codes in Fergus County
12 ZIPs touch Fergus County, Montana. The blue dashed line is the county border; orange ZIPs reach into it.
12
ZIP codes
6
cross the county line
12,156
people in these ZIPs
56
counties in MT
Most people
Fergus County ZIP list
More counties in Montana
- Chouteau County13
- Custer County7
- Daniels County5
- Dawson County8
- Deer Lodge County5
- Fallon County5
- Flathead County19
- Gallatin County14
- Garfield County9
- Glacier County5
- Golden Valley County3
- Granite County5
Questions people actually ask
How many ZIP codes are in Fergus County, Montana?
12 ZIP codes reach into Fergus County, including 1 PO Box or single-address ZIPs placed by the town they serve. 6 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Fergus County has the most people?
59457 (Lewistown) has about 9,135 residents, the most of any ZIP touching Fergus County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Fergus 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 Fergus 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