ZIP Codes of Liberty County, MT

Population & People
Population & People
Total Population
1,744
Household Income
Household Income
Median Income
$75,295
Housing
Housing
Total Housing Units
800
Business & Economy
Business & Economy
Total Businesses
66
Employment
Employment
Employment Rate
56.46%
Education
Education
Bachelor's Degree+
29.40%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 4 ZIPs in this county.
Data Last Updated: July 1, 2026
ZIP Codes:4 ZIP Codes (4 Standard, 0 PO Box, 0 Unique) [See All]
Area Code:406
Timezone:Mountain (GMT -07:00)
Local Time:11:54:12 PM
Population:1,744 [See All]
FIPS:30051
Land Area:1,330 sq mi
Water Area:3 sq mi
Coordinates:48.6476, -111.0918
Quick Link:
https://www.zip-codes.com/county/mt-liberty.asp
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Notable population decline
Lost 14.3% of residents since 2014.

Standout ZIPs in this County


Most Populous
Chester · 1,315 people
75.4% of county total
Highest Income
Whitlash · $100,781 median
1.3× county average
Largest Land Area
Chester · 875.9 sq mi
Spans the most ground
Fastest Growth
Chester · -19.3% (10-yr)
1,629 → 1,315 residents
Most Educated
— no education data

Things worth knowing about Liberty County


1,744 residents live across 4 ZIPs covering 1,330 sq mi, served by 4 distinct USPS-recognized cities.

Population moved from 2,036 to 1,744 from 2014 to 2024 — a -14.3% change. 2 ZIPs gained residents, 2 lost.

The county's wealthiest ZIP 59545 (Whitlash, $100,781 median) and poorest ZIP 59522 (Chester, $57,212) are 26.8 miles apart — a 1.8× income gap across local geography.

Median home values vary 2.7× across this county — from $110,000 in 59531 (Joplin) to $291,700 in 59545 (Whitlash).

Density varies across the county — from 0 people/sq mi in 59545 (Whitlash) to 2 in 59531 (Joplin).

Educational attainment ranges from 21.0% bachelor's+ in 59531 (Joplin) to 30.9% in 59522 (Chester) — the breadth of educational profiles across the area.

Within Montana, this is the #46 most populous of 56 counties and ranks #14 for median household income .

Weighted by population, the typical household earns about $60,782 across the county — reflecting what a typical resident sees, not a simple ZIP average.

29.4% of adults age 25+ hold a bachelor's degree or higher (351 of 1,194 reporting).

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

Stories about Liberty 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
1,330
square miles
Avg density
1.3
people per sq mi
Population
1,744
across 4 ZIPs
Chester
875.9 sq mi
1,315 residents
Joplin
232.5 sq mi
351 residents
Whitlash
114.8 sq mi
55 residents

Single-ZIP anchor

One ZIP holds the majority of this county's population — a sign of a county built around a single city or town.

Chester

Population decline

Liberty County lost 14.3% of residents between 2014 and 2024. ZIPs that shed the largest share:

Chester
-19.3%
1,629 → 1,315 residents

All ZIP Codes in Liberty County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
59522ChesterStandard1,315$57,212875.9-19.3%
59531JoplinStandard351$67,891232.52.0%
59545WhitlashStandard55$100,781114.857.1%
59461LothairStandard23106.8-17.9%

Adjacent & Nearby Counties