ZIP codes in Custer County
7 ZIPs touch Custer County, Montana. The blue dashed line is the county border; orange ZIPs reach into it.
7
ZIP codes
6
cross the county line
13,584
people in these ZIPs
56
counties in MT
Most people
Custer County ZIP list
More counties in Montana
- Blaine County10
- Broadwater County7
- Carbon County13
- Carter County8
- Cascade County21
- Chouteau County13
- Daniels County5
- Dawson County8
- Deer Lodge County5
- Fallon County5
- Fergus County12
- Flathead County19
Questions people actually ask
How many ZIP codes are in Custer County, Montana?
7 ZIP codes reach into Custer County. 6 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Custer County has the most people?
59301 (Miles City) has about 11,643 residents, the most of any ZIP touching Custer County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Custer 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 Custer 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
Updated 2026-11-10 · Where the data comes from