ZIP Codes of Jefferson County, MT

Population & People
Population & People
Total Population
13,276
Household Income
Household Income
Median Income
$96,020
Housing
Housing
Total Housing Units
5,656
Business & Economy
Business & Economy
Total Businesses
340
Employment
Employment
Employment Rate
56.72%
Education
Education
Bachelor's Degree+
31.88%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 6 ZIPs in this county.
Data Last Updated: July 1, 2026
ZIP Codes:6 ZIP Codes (4 Standard, 2 PO Box, 0 Unique) [See All]
Area Code:406
Timezone:Mountain (GMT -07:00)
Local Time:11:54:11 PM
Population:13,276 [See All]
FIPS:30043
CBSA:Helena, MT
Land Area:1,586 sq mi
Water Area:2 sq mi
Coordinates:46.1531, -112.1007
Quick Link:
https://www.zip-codes.com/county/mt-jefferson.asp
Need Jefferson data in your app? Look up ZIP, county, and city data with a single API call.
Try Free
Among Montana's 5 wealthiest counties
#2 statewide, average median income $96,020.

Standout ZIPs in this County


Most Populous
Clancy · 5,521 people
41.6% of county total
Highest Income
Clancy · $129,891 median
1.4× county average
Largest Land Area
Boulder · 477.0 sq mi
Spans the most ground
Fastest Growth
Boulder · 17.3% (10-yr)
2,179 → 2,557 residents
Most Educated
Clancy · 46.8% bachelor's+
1,805 of 3,856 adults 25+

Things worth knowing about Jefferson County


13,276 residents live across 6 ZIPs covering 1,586 sq mi, served by 6 distinct USPS-recognized cities.

Population moved from 11,905 to 13,276 from 2014 to 2024 — a +11.5% change. 4 ZIPs gained residents, 2 lost.

The county's wealthiest ZIP 59634 (Clancy, $129,891 median) and poorest ZIP 59759 (Whitehall, $60,571) are 43.9 miles apart — a 2.1× income gap across local geography.

Median home values vary 3.4× across this county — from $235,700 in 59631 (Basin) to $790,300 in 59721 (Cardwell).

Density varies 14× across the county — from 2 people/sq mi in 59721 (Cardwell) to 27 in 59634 (Clancy).

Educational attainment ranges from 17.4% bachelor's+ in 59759 (Whitehall) to 46.8% in 59634 (Clancy) — the breadth of educational profiles across the area.

Within Montana, this is the #14 most populous of 56 counties and ranks #2 for median household income with the #13 fastest decade growth .

Weighted by population, the typical household earns about $96,902 across the county — reflecting what a typical resident sees, not a simple ZIP average.

31.9% of adults age 25+ hold a bachelor's degree or higher (3,132 of 9,825 reporting).

4 Standard delivery, 2 PO Box only, 0 single-entity Unique ZIPs serve this county.

Stories about Jefferson County


Big & sparse

A frontier county — vast land area with only a few residents per square mile. Daily life looks very different here than in the country's denser counties.

Total area
1,586
square miles
Avg density
8.4
people per sq mi
Population
13,276
across 6 ZIPs
Boulder
477.0 sq mi
2,557 residents
Whitehall
440.8 sq mi
3,631 residents
Cardwell
219.8 sq mi
423 residents

All ZIP Codes in Jefferson County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
59634ClancyStandard5,521$129,891201.916.7%
59759WhitehallStandard3,631$60,571440.86.2%
59632BoulderStandard2,557$68,750477.017.3%
59638Jefferson CityPO Box769$126,72372.9-1.4%
59721CardwellStandard423$94,167219.8-24.9%
59631BasinPO Box375173.760.9%

Adjacent & Nearby Counties