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Montana County
Jefferson County, Montana
The Jefferson River - Lewis and Clark's Three Forks gateway - from the Jefferson River valley (the Jefferson River - named by Meriwether Lewis for President Thomas Jefferson on July 28, 1805 - flows through Jefferson County from the Three Forks of the Missouri to the south, and the Lewis and Clark expedition's passage through the county on their way to the Beaverhead and Continental Divide is documented at multiple sites along the river corridor) and Boulder's historic hot springs (the natural geothermal springs at Boulder have attracted visitors since the 19th century, and the Montana Department of Corrections' Boulder River School and Boulder Hot Springs reflect the community's dual heritage of mineral springs tourism and state institutional history).
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What do you need to do?
Tell us your goal and we'll guide you step-by-step to the right office, forms, and official resources.
Office: Jefferson County Office of Emergency Management/Disaster & Emergency Services – (406) 225-4035; coordinates mitigation, preparedness, response, and recovery for all-hazard incidents; uses the Everbridge Community mass notification platform for public alerts (wildfires, flooding, road closures, evacuations).
Sheriff: Jefferson County Sheriff’s Office – 110 S. Washington St., PO Box 588, Boulder, MT 59632 | (406) 225-4075 | Fax: (406) 225-4145; Sheriff Tom Grimsrud, Civil Officer Jeri Goodwin. Detention Center visitation Tue/Sat/Sun 9 AM-6 PM, 45 minutes per inmate per day, no appointment necessary.
Notes: For an active emergency, call 911.
Roads & Utilities
ROADS & TRANSPORTATION
Roads: I-15 serves Boulder, the county seat, in southwest Montana midway between Butte and Helena.
Notes: Jefferson County is bordered by Lewis and Clark County to the north, Broadwater County to the east, Gallatin County to the southeast, and Madison County to the south.
Business & Permits
BUILDING & PERMITS
Office: Jefferson County – PO Box H, Boulder, MT 59632 | confirm current phone via jeffersoncounty-mt.gov.
Notes: Boulder is genuinely home to Boulder Hot Springs – a historic 1883 resort and spa (52 rooms originally, serving wealthy families from Helena and Butte), now NRHP-listed alongside the Jefferson County Courthouse – and to multiple genuine radon health mines, including the Free Enterprise Radon Health Mine and Sunshine Health Mine, where visitors sit 85 feet underground believing the radon exposure eases certain ailments (a practice not endorsed by mainstream medicine but genuinely and continuously operating for decades). Elkhorn, a 19th-century silver boomtown that once had roughly 2,500 residents before a diphtheria epidemic and mining decline, is preserved today as Elkhorn State Park – Montana’s smallest state park, featuring the well-preserved Fraternity Hall and Gillian Hall. Boulder also unsuccessfully vied to become Montana’s state capital in the late 1800s; “Cap Hill,” where the capitol would have stood, still bears the name.
Veterans Services
VETERANS SERVICES
Office: Jefferson County Veterans Service – confirm current contact via jeffersoncounty-mt.gov.
Federal: VA Montana Health Care System (Fort Harrison/Helena, accessible north).
Libraries
LIBRARIES
Boulder Community Library – confirmed as a functioning local library serving downtown Boulder alongside grocery stores, cafes, a museum, and a senior center lunch program; confirm current hours via jeffersoncounty-mt.gov or bouldermtchamber.org.
Parks & Recreation
PARKS & RECREATION
Key Assets: Boulder Hot Springs, the radon health mines, Elkhorn State Park (ghost town), the Elkhorn Mountains, Tizer Gardens (Montana’s only Botanic Garden, near Clancy), and nearby Lewis and Clark Caverns are the county’s premier attractions.
Notes: The genuine radon health mines and the well-preserved Elkhorn ghost town are among the most distinctive local facts covered anywhere in this project.
GIS & Maps
GIS & MAPS
GIS, Maps and Rural Addressing – Jefferson County; confirm current contact via jeffersoncounty-mt.gov.
Animal Services
ANIMAL SERVICES
Confirm current animal control arrangements via jeffersoncounty-mt.gov or the Sheriff’s Office, (406) 225-4075; the Town of Whitehall requires dog licensing locally.
Environmental & Waste
ENVIRONMENTAL / WASTE MANAGEMENT
Office: Jefferson County Solid Waste – confirm current phone via jeffersoncounty-mt.gov.
NOTES: Jefferson County is the second county in the Montana v2 A+ sourced redo’s fourth batch. The genuine radon health mines and the well-preserved Elkhorn ghost town are among the most distinctive local facts covered anywhere in this project. All contact information above was sourced via web search as of early August 2026 and should be reconfirmed directly with the relevant office before a visit, deadline-sensitive filing, or emergency-adjacent decision.
About Jefferson County
Jefferson County is Lewis and Clark’s Jefferson River country – the river Meriwether Lewis named for President Jefferson on July 28, 1805 flows through one of southwest Montana’s most historically layered valleys, and Boulder’s natural hot springs and mining heritage define a community between Helena and Butte.
Boulder (the county seat, population ~1,200) and Whitehall (population ~1,000) serve Jefferson County’s agricultural and mining heritage communities in the Jefferson River valley.
All Services
Browse every category and topic available for this county.
Jefferson County Assessor (Montana Dept. of Revenue) at 204 N. Main Street, Boulder, MT 59632, phone 406-225-4020.
Courts & Legal
Jefferson County District Court at 204 N. Main Street, Boulder, MT 59632, phone 406-225-4052, handles probate.
Marriage & Vital Records
Marriage licenses, divorce records, and birth & death certificates are handled by the following office(s):
CLERK AND RECORDER
201 Centennial Ave., Boulder, MT 59632
(406) 225-4020
COUNTY CLERK (Elections)
201 Centennial Ave., Boulder, MT 59632
(406) 225-4020
Genealogy
County-level record sources
Jefferson County Clerk of District Court (probate case files – see Probate section above).
Local societies
No dedicated Jefferson County genealogical society was confirmed in available directories.
Probate & Estate
Losing someone and having to deal with courts and paperwork at the same time is hard. This section won’t make that easier, but it should tell you what to expect, what it costs, and where to go – so at least you’re not walking in blind.
Where to go
Jefferson County Clerk of District Court, Probate Division 201 W. Centennial Avenue, Boulder, MT 59632 (406) 225-4042 Jefferson County is in southwestern Montana, seated in Boulder.
Step 1: figure out which path applies
Montana adopted the Uniform Probate Code (UPC), codified at Title 72 of the Montana Code Annotated (MCA). Probate is handled by the District Court in the county where the decedent resided.
Collection of Personal Property by Affidavit (MCA § 72-3-1101) – available when the value of the probate estate, less liens and encumbrances, does not exceed $100,000. At least 30 days must have passed since the death, and no application or petition for appointment of a personal representative may be pending or granted anywhere. The affiant presents the sworn, notarized affidavit (with a certified death certificate) directly to whoever holds the property to collect it – skipping probate court entirely. Must be used within 3 years of death.
Summary Administration – a streamlined court process for estates valued at $100,000 or less; unlike the affidavit procedure, this still goes through the court, just with reduced formality.
Informal Probate – the most common path for uncontested estates. An application can be made to the clerk of district court no sooner than 120 hours (5 days) after death, with minimal court involvement.
Formal Probate – required when there’s no will, when a will’s validity is contested, or when there’s disagreement over the personal representative or distribution. Handled by a district court judge.
Supervised Administration – formal probate with ongoing court oversight of the personal representative.
Step 2: filing for formal or informal probate
File an application (informal) or petition (formal) with the Clerk of District Court in the county where the decedent resided, no sooner than 120 hours after death.
The court or clerk appoints the personal representative and issues Letters Testamentary or Letters of Administration.
The personal representative publishes notice to creditors and gives direct notice to known creditors. Creditors generally have 4 months from the date of first publication to file claims.
The personal representative inventories and appraises the estate’s assets.
After debts, taxes, and expenses are paid and the creditor claim period expires, the personal representative distributes the remaining assets and closes the estate.
What it costs
Montana does not set statutory percentage-based fees; personal representative and attorney fees are generally “reasonable compensation” based on time and complexity.
Montana has no state estate tax and no state inheritance tax. Only the federal estate tax could apply, and only to very large estates.
Probate filings, estate administration, and guardianship matters are handled by the following office(s):
Public Safety & Arrests
Arrest records, inmate search, and law enforcement services are handled by the following office(s):
SHERIFF
201 Centennial Ave., Boulder, MT 59632
(406) 225-4075
Elections & Voting
Voter registration, polling locations, and elections information are handled by the following office(s):
COUNTY CLERK (Elections)
201 Centennial Ave., Boulder, MT 59632
(406) 225-4020
ELECTIONS
201 Centennial Ave., Boulder, MT 59632
(406) 225-4020
Health & Human Services
Offices & Contacts
Health services, social services, and assistance programs are handled by the following office(s):
Office: Jefferson County Health Department – (406) 225-4009 | confirm current address via jeffersoncounty-mt.gov.
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Editorial Trust
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Last verified June 2026
County Facts
County Seat: Boulder
Population: 12,500
Area: 1,656 sq mi
Established: 1865
Tier: 3
Public Records
TruthFinder
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