Every ZIP code in the United States, with weather, radar, trivia and the numbers behind it. Five digits since 1963!

ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — STATE/MT/COUNTY/JEFFERSON

Jefferson County, MT ZIP codes

Jefferson County, MT has 6 ZIP codes, in 6 towns: 59634, 59759, 59632, 59721, 59631 and 59638. 1 more crosses into it from a neighbouring county: 59701.

The county seat is Boulder.

ZIP codes
6
Partly in it
1 more
Towns
6
County seat
Boulder
County FIPS
30043
State
Montana
Population
12,774
Median household income
$95,490
Land area
1,657 sq mi
Metro area
Helena

Jefferson County ZIP codes by town

Boulder (county seat)
59632

Each ZIP code is listed under the county most of its land lies in and the town the Postal Service names it for; a ZIP code's own page shows exactly how it is split.

ZIP codes partly in Jefferson County

This ZIP code lies mostly in a neighbouring county but covers a twentieth or more of Jefferson County.

Map of Jefferson County ZIP codes

596315963259634596385972159759

The ZIP codes of Jefferson County, shaded. Outlines are Census ZIP Code Tabulation Areas (2020), which approximate the mail routes; PO-box and single-address codes have no area and are not drawn. Click any area to open its ZIP code.

Jefferson County in numbers

About 12,774 people live in Jefferson County, in 4,996 households, the 16th most populous of Montana's 56 counties. The median household income is $95,490 a year, 32% above the Montana median of $72,509 (US: $80,734). The median owner-occupied home is valued at $446,900 (19% above the Montana median), and median gross rent is $925 a month. The median age is 47.1; 32.2% of adults 25 and over hold a bachelor's degree or higher (35.2% across Montana); the average commute takes 24 minutes.

Population12,774Jefferson12,774
Households4,996Jefferson4,996
Median age47.1Jefferson47.1Montana40.4US 38.9
Median household income$95,490Jefferson$95,490Montana$72,509US $80,734
Median home value$446,900Jefferson$446,900Montana$375,800US $332,700
Median gross rent$925Jefferson$925Montana$1,081US $1,413
Bachelor's degree or higher32.2%Jefferson32.2%Montana35.2%US 35.7%
Mean commute24.4 minJefferson24.4 minMontana19.1 minUS 26.4 min
Population density8 / sq miJefferson8 / sq mi

U.S. Census Bureau, American Community Survey 2020–2024 5-year estimates. Survey estimates carry margins of error, wider for small places. Sources and methods.

Largest towns in Jefferson County

Largest towns in Jefferson County
TownZIP codesPopulation
Clancy 1 1,874
Boulder 1 1,284
Whitehall 1 1,156
Jefferson City 1 533
Basin 1 352
Cardwell 1 30

Population of the census place of that name where there is one, otherwise of the ZIP codes the Postal Service addresses by it. A town's ZIP codes can reach past the county line.

Neighbouring counties

Counties that share a ZIP code with Jefferson County.

Not sure you are in Jefferson County? What county am I in? answers from your location, near a county line included.

Every ZIP code in Jefferson County, with figures

ZIP codes in Jefferson County
ZIP City Type Population Median income Median home
59631 Basin , MT Standard 375 — $235,700
59632 Boulder , MT Standard 2,557 $68,750 $278,800
59634 Clancy , MT Standard 5,521 $129,891 $553,900
59638 Jefferson City , MT Standard 769 $126,723 —
59721 Cardwell , MT Standard 423 $94,167 $790,300
59759 Whitehall , MT Standard 3,631 $60,571 $353,900

Cite this page

zipcodes.pro. “Jefferson County ZIP codes.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/state/mt/county/jefferson

Underlying data is public domain or openly licensed — sources, vintages and licences.