Montana

Jefferson

12,085
2020 population
1870
first census record
16
census records

About Jefferson

Jefferson, Montana, first appears in the United States federal census in 1870, when it recorded a population of 1,531. At the most recent census, in 2020, its population stood at 12,085.

The county's recorded population has risen across the decades to its highest level in 2020.

On the ground today, 15 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
202012,085
201011,406
200010,049
19907,939
19807,029
19705,238
19604,297
19504,014
19404,664
19304,133
19205,203
19105,601
19005,330
18906,026
18802,464
18701,531
Source

Population data from the United States decennial census, U.S. Census Bureau (public domain).

Historic places in Jefferson

National Register of Historic Places listings in Jefferson, Montana.

Montana State Training School Historic District
Boulder
MacHaffie Site (24JF4)
Montana City
Child, W. C., Ranch
East Helena
Jefferson County Courthouse
Boulder
Fraternity Hall
Elkhorn
Browse all Montanahistoric sites ›

Other counties in Montana

Explore census history and historic records for more Montana counties.

BlaineBroadwaterCarbonCarterCascadeChouteauCusterDanielsDawsonDeer LodgeFallonFergusFlatheadGallatinGarfieldGlacierGolden ValleyGraniteHillJudith Basin
Unlimited access

Everything a full report reveals about Jefferson County, Montana

This page charts the census history of Jefferson County, Montana. A full Aubrey report for an address here pulls together everything the historical record holds about the ground, from the earliest settlement to the twentieth century:

Overview
An interactive map of the location with historic sites, battles and Native heritage plotted, and its full story era by era.
The Land
The historic sites and place names around the location, and how this land was settled and used.
Geology
The bedrock beneath the site, its age and rock type, reaching back millions of years.
LiDAR Terrain
Laser-scanned terrain that reveals earthworks and old features hidden in the landscape.
Conflict & War
The battles, raids and skirmishes fought near here, across every era of American conflict.
The Civil War
The Civil War on this ground, 1861 to 1865: who held it, and the battles, camps and regiments nearby.
The Soldiers
The men who marched from here in the Civil War, named and traced where the record allows.
Native Heritage
The Native nations who held this land, mapped across time from before European contact to today.
Settlement
Who claimed and held this ground, from Indigenous homelands through the colonial powers to the United States.
The Community
How the town grew, who came, and what kind of place it became, traced through the census record.
Rivers & Rail
The rivers, canals and railroads that connected this place between 1830 and 1911.
Notable People
The people born, buried or genuinely tied to this exact place, with their stories.
Historical Maps
Historic maps of the location layered over how it looks today.
Finds & Access
Museum objects tied to the area, and the laws on searching, collecting and access here.
Literature
The old books, county histories and archives that mention this place, quoted with their sources.
Spotlight
A deep dive into the most remarkable, lesser-known history of the place, traced back to the record.
Points of Interest
The most significant historic sites and landmarks near the location, and why they matter.
Timeline
The whole story of the location told era by era, from first peoples to the present day.
First month just $5.99, then $11.99 a month. Unlimited locations, cancel anytime.

Every location is different. Not every section appears for every place, only what the historical record actually holds turns up in a report.

Start your Jefferson County, Montana report
Or see a real report first

Explore Montana records

Montanahistory ›NRHP historic sites ›Notable people from Montana›

Frequently asked about Jefferson

When does Jefferson first appear in the US census?
Jefferson, Montana first appears in the federal census in 1870, with a recorded population of 1,531.
What is the population of Jefferson?
At the most recent federal census (2020), Jefferson had a recorded population of 12,085.
How many historic places are in Jefferson?
15 sites are listed on the National Register of Historic Places in Jefferson, Montana.
Aubrey Research

Research the history of any US location

Aubrey searches federal archives, archaeological records, historic registers, and primary sources to build a full historical report for any address or place in the United States.

Research your locationView a free sample report