4,597 people (2024 Census estimate, +7.7% since 2020)
4,922 square miles of land · 1 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.
4 active community water systems list Custer County in the area they serve, reporting 1,618 people served in all (a system that crosses county lines counts its whole population).
| CHALLIS CITY OF surface water · local government · ID7190013 | 900 served |
| MACKAY CITY OF groundwater · local government · ID7190032 | 566 served |
| ROUND VALLEY WATER ASSN groundwater · private · ID7190042 | 125 served |
| ANTELOPE CREEK LIVING CENTER groundwater · private · ID7190001 | 27 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 4 people were held in Custer County's jail, in Vera's latest figure (2019), or 163 per 100,000 residents ages 15–64. In 2014 it was about 5.
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.
2 school districts have their office in Custer County. School taxes are usually the largest part of a property tax bill.
Spent $5.4 million — $4.7 million to run schools, about $14,317 per student, plus $690,000 on buildings and equipment. Money in: $1.3 million local (mostly property tax), $3.1 million state, $1.3 million federal.
Spent $3.7 million — $2.8 million to run schools, about $11,983 per student, plus $712,000 on buildings and equipment. Money in: $562,000 local (mostly property tax), $2.5 million state, $858,000 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: Relatively Low compared with other U.S. counties. FEMA estimates natural hazards cost Custer County about $10.6 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very Low; social vulnerability: Very High.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
126 bridges in Custer County: 40 in good condition, 72 fair, and 14 poor (11.1%). “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.
| SH 75 over YANKEE FK OF SALMON RIVR · built 1934 | 680 vehicles a day |
| SQUAW CREEK ROAD over SQUAW CREEK · built 1960 | 330 vehicles a day |
| SQUAW CREEK RD over SQUAW CREEK · built 1960 | 330 vehicles a day |
| SQUAW CREEK RD over SQUAW CREEK · built 1960 | 300 vehicles a day |
| SQUAW CREEK RD over SQUAW CREEK · built 1960 | 100 vehicles a day |
| CUSTER MOTORWAY over YANKEE FORK · built 1992 | 100 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $16.5 million of work in Custer County in fiscal 2025, about $3,864 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 Idaho 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 Custer 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 Custer County built: brayden.ozark@gmail.com.
More of Idaho: the state government and every county in Idaho.
Nearby counties: Lemhi County (49 mi) · Camas County (59 mi) · Blaine County (62 mi) · Butte County (67 mi) · Boise County (75 mi) · Valley County (79 mi).