13,304 people (2024 Census estimate, +9.6% since 2020)
1,657 square miles of land · 8 people per square mile
“Highest” and “lowest” are just order, not grades: a high rank for poverty or hazard losses means more of it. Each figure's source is in its section below.
14 active community water systems list Jefferson County in the area they serve, reporting 5,400 people served in all (a system that crosses county lines counts its whole population).
| WHITEHALL TOWN OF groundwater · local government · MT0000359 | 1,500 served |
| BOULDER CITY OF groundwater · local government · MT0000158 | 1,400 served |
| JEFFERSON HILLS WUA groundwater · private · MT0002978 | 780 served |
| SADDLE MOUNTAIN CORP CLANCY groundwater · private · MT0000057 | 350 served |
| FOREST PARK WATER USERS ASSOCIATION groundwater · private · MT0000591 | 323 served |
| BLUE SKY HEIGHTS WUA CLANCY groundwater · private · MT0000030 | 250 served |
| BASIN COUNTY WATER AND SEWER DIST groundwater · public/private · MT0000014 | 200 served |
| HANGMANS TREE WUA groundwater · private · MT0000128 | 158 served |
Source: U.S. EPA Safe Drinking Water Information System (SDWIS), active community systems, . Look up any system's violations and test results with EPA's search using its ID.
About 7 people were held in Jefferson County's jail, in Vera's latest figure (2021), or 92 per 100,000 residents ages 15–64. In 2016 it was about 20.
Source: Vera Institute of Justice, Incarceration Trends (built from federal Bureau of Justice Statistics jail surveys). Counties without their own jail, or that share one, may show no figure.
8 school districts have their office in Jefferson County. School taxes are usually the largest part of a property tax bill.
Spent $5.3 million — $5.1 million to run schools, about $10,735 per student, plus $119,000 on buildings and equipment. Money in: $2.7 million local (mostly property tax), $2.8 million state, $320,000 federal. Long-term debt: $3.7 million.
Spent $3.9 million — $3.6 million to run schools, about $9,384 per student, plus $219,000 on buildings and equipment. Money in: $1.3 million local (mostly property tax), $2.1 million state, $387,000 federal. Long-term debt: $51,000.
Spent $4.5 million — $4.1 million to run schools, about $12,485 per student, plus $164,000 on buildings and equipment. Money in: $1.2 million local (mostly property tax), $1.9 million state, $1.4 million federal.
Spent $6.8 million — $4.3 million to run schools, about $15,208 per student, plus $1.8 million on buildings and equipment. Money in: $3.2 million local (mostly property tax), $2.1 million state, $788,000 federal. Long-term debt: $14.8 million.
Spent $3.7 million — $3.4 million to run schools, about $15,697 per student, plus $220,000 on buildings and equipment. Money in: $1.2 million local (mostly property tax), $1.2 million state, $1.1 million federal. Long-term debt: $83,000.
Spent $1.9 million — $1.8 million to run schools, about $12,660 per student, plus $95,000 on buildings and equipment. Money in: $1.3 million local (mostly property tax), $1.1 million state, $47,000 federal.
Spent $728,000 — $609,000 to run schools, about $15,225 per student, plus $101,000 on buildings and equipment. Money in: $312,000 local (mostly property tax), $201,000 state, $93,000 federal.
Spent $464,000 — $432,000 to run schools, about $39,273 per student, plus $32,000 on buildings and equipment. Money in: $153,000 local (mostly property tax), $123,000 state, $222,000 federal.
Source: U.S. Census Bureau, 2023 Annual Survey of School System Finances. Districts are listed by the county of their main office; some serve neighboring counties too.
Source: County Health Rankings & Roadmaps 2025 (University of Wisconsin Population Health Institute), which gathers federal data (CDC, Census, and others); measures cover different recent years. Blank lines aren't reported for small counties.
Overall risk: Very Low compared with other U.S. counties. FEMA estimates natural hazards cost Jefferson County about $8.6 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively Low; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
136 bridges in Jefferson County: 26 in good condition, 103 fair, and 7 poor (5.1%). “Poor” means a main part — the deck, the beams, or the supports — is rated 4 or lower on the federal 0–9 scale. It doesn't mean unsafe to drive; unsafe bridges are closed.
| MT 55 over FISH CREEK · built 1953 | 1,858 vehicles a day |
| MT HWY 2 over RR 061 · built 1932 | 1,001 vehicles a day |
| SLEEPY HOLLOW LN over PRICKLY PEAR CREEK · built 2010 | 100 vehicles a day |
| I 15 FRONTAGE RD over CATARACT CREEK 030 · built 1933 | 100 vehicles a day |
| I 15 FRONTAGE RD over BASIN CREEK 041 · built 1985 | 100 vehicles a day |
| E ELK PARK RD over BISON CREEK 016 · built 1927 | 100 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $6.4 million of work in Jefferson County in fiscal 2025, about $532 per resident — to the county, cities, schools, hospitals, nonprofits and others.
Source: USAspending.gov, grants by place of performance, fiscal 2025 (Oct. 2024 to Sept. 2025). Search it by county to see each award.
From Grants.gov: posted grants listing county governments as eligible, soonest deadline first; research-only and overseas programs left out; list updated 2026-10-13, refreshed weekly. 62 are open in all. Cities, towns, school districts and nonprofits have their own lists there.
Registration deadlines, early voting and polling places for Montana are on the federal site vote.gov, which links to the state's official election office.
The budget, property tax rates, audits, local officials and offices for Jefferson County come from the county's own records, which we haven't gathered — not gathered, never hidden. See what a full county site looks like, or ask to have Jefferson County built: brayden.ozark@gmail.com.
More of Montana: the state government and every county in Montana.
Nearby counties: Broadwater County (30 mi) · Silver Bow County (33 mi) · Deer Lodge County (52 mi) · Madison County (56 mi) · Gallatin County (60 mi) · Meagher County (63 mi).