Jefferson County, Administrative county in southwestern Montana, United States.
Jefferson County is an administrative county in southwestern Montana, positioned between the cities of Helena and Butte. The area includes portions of two national forests and supports a number of small communities within its boundaries.
The county was established in 1865 and named after President Thomas Jefferson. This founding occurred during a period of growth and development in the western United States.
The Boulder community functions as both the county seat and central location for governmental operations, serving a population of over 12,000 residents.
Major routes including Interstate 15, Interstate 90, U.S. Highway 12, and U.S. Highway 287 run through the county. These roads make it straightforward to travel between communities and reach neighboring regions.
The Sheriff's Office maintains a CodeRED emergency notification system that delivers immediate alerts about safety concerns to county inhabitants.
Location: Montana
Inception: February 2, 1865
Capital city: Boulder
Shares border with: Lewis and Clark County, Silver Bow County, Madison County, Deer Lodge County, Powell County, Broadwater County, Gallatin County
Website: http://jeffco.mt.gov
GPS coordinates: 46.18000,-112.11000
Latest update: December 8, 2025 13:43
Our Lady of the Rockies
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Dumas Brothel
37.7 km
Lewis and Clark Caverns
44.5 kmMontana Governor's Residence
45.6 km
Columbia Gardens
33.5 km
Mai Wah Museum
38.2 km
Helena Historic District
44.4 km
Butte-Anaconda Historic District
42.8 km
Lewis & Clark Caverns State Park
43 km
World Museum of Mining
39.9 km
Socialist Hall
37.3 km
Burton K. Wheeler House
37.1 km
W.C. Child Ranch
45.8 km
Eagle Guard Station
34.7 km
Fraternity Hall
16.5 km
Porter Flats Apartments
45.7 km
Jefferson County Courthouse
6.3 km
Morris Silverman House
45.9 km
T. H. Kleinschmidt House
45.5 km
Robert and Elizabeth Fisk House
45.8 km
Ringing Rocks
28.1 km
Lewis and Clark Caverns State Park
43 km
Star Theatre
34.5 km
Bleu Horses
45.7 km
Former Montana Executive Mansion
45.8 km
Cave Visitor Center
42.4 km
Guardian of the Gulch
45.4 km
Lewis and Clark Caverns Historic District
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