231,888 people (2024 Census estimate, +2.2% since 2020)
656 square miles of land · 353 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.
68 active community water systems list Jefferson County in the area they serve, reporting 182,793 people served in all (a system that crosses county lines counts its whole population).
| JEFFERSON CO CONS PWSD C 1 buys surface water · local government · MO6024295 | 37,000 served |
| JEFFERSON COUNTY PWSD 1 buys surface water · local government · MO6024292 | 21,113 served |
| JEFFERSON COUNTY PWSD 3 buys surface water · local government · MO6024294 | 17,000 served |
| JEFFERSON COUNTY PWSD 2 surface water · local government · MO6024293 | 16,548 served |
| FESTUS PWS buys groundwater · local government · MO6010276 | 13,000 served |
| JEFFERSON COUNTY PWSD 10 buys surface water · local government · MO6024302 | 10,000 served |
| JEFFERSON COUNTY PWSD 5 groundwater · local government · MO6024296 | 8,000 served |
| JEFFERSON COUNTY PWSD 6 groundwater · local government · MO6024298 | 7,500 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 319 people were held in Jefferson County's jail, in Vera's latest figure (2019), or 215 per 100,000 residents ages 15–64. In 2014 it was about 286.
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.
11 school districts have their office in Jefferson County. School taxes are usually the largest part of a property tax bill.
Spent $157.1 million — $129.7 million to run schools, about $12,111 per student, plus $23.5 million on buildings and equipment. Money in: $65.3 million local (mostly property tax), $72.1 million state, $12.4 million federal. Long-term debt: $59.8 million.
Spent $73 million — $68.9 million to run schools, about $11,537 per student, plus $2.3 million on buildings and equipment. Money in: $38.6 million local (mostly property tax), $37.3 million state, $6.4 million federal. Long-term debt: $30.1 million.
Spent $34.7 million — $31.9 million to run schools, about $9,612 per student, plus $2.2 million on buildings and equipment. Money in: $17.9 million local (mostly property tax), $20.5 million state, $4.1 million federal.
Spent $40.3 million — $34.8 million to run schools, about $10,585 per student, plus $4.3 million on buildings and equipment. Money in: $19.2 million local (mostly property tax), $21.6 million state, $6.2 million federal. Long-term debt: $19.6 million.
Spent $37.4 million — $33 million to run schools, about $11,191 per student, plus $2.6 million on buildings and equipment. Money in: $18.5 million local (mostly property tax), $18.7 million state, $3.5 million federal. Long-term debt: $22.4 million.
Spent $33.8 million — $30.6 million to run schools, about $12,019 per student, plus $2.1 million on buildings and equipment. Money in: $15.3 million local (mostly property tax), $18 million state, $3.2 million federal. Long-term debt: $22.7 million.
Spent $22.4 million — $21.3 million to run schools, about $8,923 per student, plus $786,000 on buildings and equipment. Money in: $4.9 million local (mostly property tax), $17.7 million state, $1.9 million federal. Long-term debt: $5.7 million.
Spent $23.7 million — $21.8 million to run schools, about $13,770 per student, plus $536,000 on buildings and equipment. Money in: $13.1 million local (mostly property tax), $11.7 million state, $3.8 million federal. Long-term debt: $19.7 million.
And 3 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 Jefferson County about $114.5 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Very Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
410 bridges in Jefferson County: 143 in good condition, 257 fair, and 10 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.
| US 61 S over BRAUHN CR · built 1923 | 5,707 vehicles a day |
| US 61 S over BR OF BRAUHN CR · built 1900 | 5,707 vehicles a day |
| US 61 S over GIBSON CR · built 1935 | 5,707 vehicles a day |
| US 61 S over JOACHIM CR · built 1933 | 4,488 vehicles a day |
| EIME RD over TRIB OF BIG RVR · built 1900 | 305 vehicles a day |
| DE WITT ST over TANYARD BR · built 1900 | 300 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $38.7 million of work in Jefferson County in fiscal 2025, about $171 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 Missouri 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 Missouri: the state government and every county in Missouri.
Nearby counties: Monroe County, IL (20 mi) · St. Louis County (27 mi) · Washington County (29 mi) · Franklin County (31 mi) · St. Louis city (31 mi) · St. Francois County (31 mi).