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Office: Petroleum County – confirm current DES contact via petroleumcountymt.org.
Sheriff: Petroleum County Sheriff’s Department – 201 East Main / 302 East Main, Winnett, MT 59087 | (406) 429-6551 | Email: [email protected]; Sheriff Dan Linder. As of recent reporting, the county has zero registered sex/violent offenders. Petroleum County Search and Rescue is an all-volunteer unit of about 12 members led by the Sheriff, capable of high-angle rope rescue and search operations in the rugged Missouri Breaks terrain of northern Petroleum County.
Notes: For an active emergency, call 911.
Roads & Utilities
ROADS & TRANSPORTATION
Roads: MT-244 serves Winnett, the county seat, in central Montana.
Notes: Petroleum County is genuinely Montana’s least populous county (roughly 500-550 residents) and was the last of the state’s 56 counties to be organized, partitioned from Fergus County on February 25, 1925. It is also the eighth-least populous county in the entire United States.
Business & Permits
BUILDING & PERMITS
Office: Petroleum County Clerk and Recorder – 302 East Main, PO Box 226, Winnett, MT 59087-0226 | (406) 429-5311 | Fax: (406) 429-6328.
Notes: The county’s name derives from petroleum fields discovered in the area in the early 20th century. Prior to settlement, the region was home to the Crow, Blackfoot, Nez Perce, and Sioux peoples. Northern Petroleum County includes portions of the Missouri Breaks, a rugged badlands terrain along the Missouri River.
Veterans Services
VETERANS SERVICES
Office: Petroleum County Veterans Service – confirm current contact via petroleumcountymt.org.
Federal: VA Montana Health Care System (Fort Harrison/Helena, accessible west).
Libraries
LIBRARIES
Petroleum Public Library – 305 S. Broadway, Winnett, MT 59087 | (406) 429-2451.
Parks & Recreation
PARKS & RECREATION
Key Assets: The Missouri Breaks (in the county’s rugged north) and the surrounding prairie and badlands landscape are the county’s primary natural draws.
Notes: The genuine status of Petroleum County as Montana’s least populous county – and the last of the state’s 56 counties to be formed – is a distinctive local fact.
GIS & Maps
GIS & MAPS
Appraisal/Parcel Search: Petroleum County Assessor – 302 East Main, Winnett, MT 59087; confirm current phone via petroleumcountymt.org.
Animal Services
ANIMAL SERVICES
Confirm current animal control arrangements via petroleumcountymt.org or the Sheriff’s Department, (406) 429-6551.
Environmental & Waste
ENVIRONMENTAL / WASTE MANAGEMENT
Office: Petroleum County Road/Weed Department – confirm current phone via petroleumcountymt.org.
NOTES: Petroleum County is the first county in the Montana v2 A+ sourced redo’s sixth batch. The genuine status of Petroleum County as Montana’s least populous county and the last of the state’s 56 counties to be organized is a distinctive local fact. 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 Petroleum County County
Petroleum County is Montana’s least populous county – fewer than 500 residents in 1,654 square miles of Musselshell River badlands where Winnett serves the scattered cattle ranching families in one of the most remote and least-visited landscapes in the contiguous United States.
Winnett (the county seat, population ~170) is Petroleum County’s governmental hub, one of the smallest county seats in America – a tiny central Montana community whose oil heritage name, Musselshell badlands, and cattle ranching economy define an extraordinary remoteness.
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Petroleum County Assessor at 201 E. Main Street, Winnett, MT 59087, phone 406-429-5311. MT assessed at market value.
Courts & Legal
Petroleum County District Court at 201 E. Main Street, Winnett, MT 59087, phone 406-429-5311, handles probate.
Marriage & Vital Records
Marriage licenses, divorce records, and birth & death certificates are handled by the following office(s):
CLERK AND RECORDER
201 E. Main St., Winnett, MT 59087
(406) 429-5311
COUNTY CLERK (Elections)
201 E. Main St., Winnett, MT 59087
(406) 429-5311
Genealogy
County-level record sources
Petroleum County Clerk of District Court (probate case files – see Probate section above).
The Winnett Block, NRHP-listed (built 1917-18), became the Petroleum County Courthouse in 1928.
Local societies
No dedicated Petroleum 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
Petroleum County Clerk of District Court, Probate Division 302 East Main Street (mail: P.O. Box 226), Winnett, MT 59087 (406) 429-5105
Petroleum County was founded February 25, 1925, named for the petroleum fields in the area, in central Montana, seated in Winnett. It is Montana’s least populous county.
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 E. Main St., Winnett, MT 59087
(406) 429-5311
Elections & Voting
Voter registration, polling locations, and elections information are handled by the following office(s):
COUNTY CLERK (Elections)
201 E. Main St., Winnett, MT 59087
(406) 429-5311
ELECTIONS
201 E. Main St., Winnett, MT 59087
(406) 429-5311
Health & Human Services
Offices & Contacts
Health services, social services, and assistance programs are handled by the following office(s):
MT DPHHS — Petroleum
(406) 429-5311
Public Health Information
PUBLIC HEALTH
Office: Petroleum County Telehealth Center – 302 East Main, Winnett, MT 59087; confirm current phone via petroleumcountymt.org.
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Last verified June 2026
County Facts
County Seat: Winnett
Population: 490
Area: 1,654 sq mi
Established: 1925
Public Records
TruthFinder
Search public records for Petroleum County County residents.
