171,583 people (2024 Census estimate, +3.9% since 2020)
2,633 square miles of land · 65 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.
54 active community water systems list Yellowstone County in the area they serve, reporting 152,067 people served in all (a system that crosses county lines counts its whole population).
| BILLINGS CITY OF surface water · local government · MT0000153 | 114,000 served |
| BILLINGS HEIGHTS CO WATER DIST OF buys surface water · local government · MT0000155 | 12,000 served |
| LAUREL MUNICIPAL WATER SYSTEM surface water · local government · MT0000270 | 6,339 served |
| LOCKWOOD WATER AND SEWER DISTRICT surface water · local government · MT0000156 | 5,900 served |
| PIONEER WATER SERVICE buys surface water · private · MT0004226 | 900 served |
| GO 2 U WATER DELIVERY buys surface water · private · MT0004754 | 875 served |
| WORDEN BALLANTINE YELLOWSTONE groundwater · local government · MT0000022 | 800 served |
| ESTATES AT YELLOWSTONE LLC groundwater · private · MT0000464 | 800 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 445 people were held in Yellowstone County's jail, in Vera's latest figure (2021), or 421 per 100,000 residents ages 15–64. In 2016 it was about 446.
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.
19 school districts have their office in Yellowstone County. School taxes are usually the largest part of a property tax bill.
Spent $141.1 million — $132 million to run schools, about $12,015 per student, plus $3.4 million on buildings and equipment. Money in: $60.8 million local (mostly property tax), $67.4 million state, $21.8 million federal. Long-term debt: $116.2 million.
Spent $72.3 million — $68.6 million to run schools, about $12,233 per student, plus $1.1 million on buildings and equipment. Money in: $34.8 million local (mostly property tax), $35.1 million state, $5.8 million federal. Long-term debt: $11.5 million.
Spent $22.9 million — $20.1 million to run schools, about $11,727 per student, plus $185,000 on buildings and equipment. Money in: $12.1 million local (mostly property tax), $10.2 million state, $4.1 million federal. Long-term debt: $59.2 million.
Spent $17.8 million — $15.8 million to run schools, about $12,438 per student, plus $1.9 million on buildings and equipment. Money in: $6.6 million local (mostly property tax), $6.8 million state, $3.6 million federal. Long-term debt: $2.9 million.
Spent $14.1 million — $12 million to run schools, about $15,530 per student, plus $1.2 million on buildings and equipment. Money in: $4.9 million local (mostly property tax), $5.1 million state, $3.3 million federal. Long-term debt: $9.7 million.
Spent $7.3 million — $6.5 million to run schools, about $9,504 per student, plus $22,000 on buildings and equipment. Money in: $3.6 million local (mostly property tax), $4 million state, $442,000 federal. Long-term debt: $17.3 million.
Spent $8 million — $7.2 million to run schools, about $11,553 per student, plus $754,000 on buildings and equipment. Money in: $4.4 million local (mostly property tax), $3.9 million state, $46,000 federal. Long-term debt: $1.5 million.
Spent $6.8 million — $5.7 million to run schools, about $10,165 per student, plus $566,000 on buildings and equipment. Money in: $2.7 million local (mostly property tax), $3.4 million state, $762,000 federal. Long-term debt: $8.5 million.
And 11 more.
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: Relatively Moderate compared with other U.S. counties. FEMA estimates natural hazards cost Yellowstone County about $60.1 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
290 bridges in Yellowstone County: 97 in good condition, 186 fair, and 7 poor (2.4%). “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.
| MONTANA AVE over U1025-RR · built 1960 | 8,576 vehicles a day |
| MONTANA AVE over U1024-25-RR · built 1960 | 8,576 vehicles a day |
| OLD HWY 312 over YELLOWSTONE RIVER 170 · built 1949 | 4,005 vehicles a day |
| S SHILOH RD over SEP I 90 · built 1959 | 3,188 vehicles a day |
| OLD US 10 over BIG DITCH 051 · built 1932 | 2,489 vehicles a day |
| W I RD over CUSTER COULEE 098 · built 1962 | 100 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $69 million of work in Yellowstone County in fiscal 2025, about $419 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 Yellowstone 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 Yellowstone County built: brayden.ozark@gmail.com.
More of Montana: the state government and every county in Montana.
Nearby counties: Musselshell County (40 mi) · Big Horn County (52 mi) · Treasure County (52 mi) · Golden Valley County (53 mi) · Stillwater County (56 mi) · Carbon County (61 mi).