ZIP codes in Lewis and Clark County
16 ZIPs touch Lewis and Clark County, Montana. The blue dashed line is the county border; orange ZIPs reach into it.
16
ZIP codes
3
cross the county line
75,997
people in these ZIPs
56
counties in MT
Most people
Lewis and Clark County ZIP list
More counties in Montana
- Golden Valley County3
- Granite County5
- Hill County10
- Jefferson County9
- Judith Basin County12
- Lake County15
- Liberty County7
- Lincoln County7
- Madison County18
- McCone County6
- Meagher County4
- Mineral County6
Questions people actually ask
How many ZIP codes are in Lewis and Clark County, Montana?
16 ZIP codes reach into Lewis and Clark County, including 4 PO Box or single-address ZIPs placed by the town they serve. 3 of them are only partly in the county and also cover a neighboring county.
Which ZIP code in Lewis and Clark County has the most people?
59601 (Helena) has about 31,728 residents, the most of any ZIP touching Lewis and Clark County, in the Census Bureau’s ACS 2020–2024 estimates.
Can a ZIP code be in Lewis and Clark 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 Lewis and Clark 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