269,136 people (2024 Census estimate, +7.8% since 2020)
583 square miles of land · 462 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.
7 active community water systems list Williamson County in the area they serve, reporting 252,925 people served in all (a system that crosses county lines counts its whole population).
| FRANKLIN WATER DEPT surface water · local government · TN0000246 | 77,222 served |
| H.B.& T.S. UTILITY DISTRICT buys surface water · local government · TN0000699 | 40,094 served |
| MILCROFTON UTILITY DISTRICT buys surface water · local government · TN0000247 | 38,032 served |
| NOLENSVILLE-COLLEGE GROVE U.D. buys surface water · local government · TN0000511 | 34,159 served |
| MALLORY VALLEY U.D. buys surface water · local government · TN0000428 | 31,703 served |
| BRENTWOOD WATER DEPARTMENT buys surface water · local government · TN0000069 | 30,645 served |
| GATEWAY UTILITY COMPANY, INC. buys surface water · private · TN0008271 | 1,070 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 316 people were held in Williamson County's jail, in Vera's latest figure (2024), or 185 per 100,000 residents ages 15–64. In 2019 it was about 383.
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 Williamson County. School taxes are usually the largest part of a property tax bill.
Spent $672.5 million — $501.8 million to run schools, about $11,899 per student, plus $142.6 million on buildings and equipment. Money in: $469.7 million local (mostly property tax), $157.3 million state, $20.5 million federal. Long-term debt: $556.8 million.
Spent $78.5 million — $60.3 million to run schools, about $18,909 per student, plus $12.9 million on buildings and equipment. Money in: $53.8 million local (mostly property tax), $15.7 million state, $5.8 million federal. Long-term debt: $68.1 million.
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 Williamson County about $98 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Very Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
531 bridges in Williamson County: 341 in good condition, 174 fair, and 16 poor (3.0%). “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.
| I65 over BRANCH · built 1963 | 109,713 vehicles a day |
| I65 over I65 / SR106 & HARPETH RV · built 1963 | 94,031 vehicles a day |
| I65 over I65 / SR106 & HARPETH RV · built 1963 | 94,031 vehicles a day |
| FAP 96 over SR 96 / I65 · built 1962 | 31,982 vehicles a day |
| FAP 96 over HARPETH RIVER · built 1958 | 19,656 vehicles a day |
| FAU 441 RAMP C over RAMP C/RAMP B COOL SPNG · built 1991 | 17,725 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $19.8 million of work in Williamson County in fiscal 2025, about $80 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.
General election: Tuesday, November 3, 2026. Last day to register to vote: 2026-10-05. Early voting: 2026-10-14 to 2026-10-29. Mail ballot request deadline: 2026-10-24. Election Day: 2026-11-03.
Source: Tennessee Secretary of State: elections calendar · Tennessee Secretary of State: registration deadline FAQ · Tennessee Secretary of State: GoVoteTN
The budget, property tax rates, audits, local officials and offices for Williamson 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 Williamson County built: brayden.ozark@gmail.com.
More of Tennessee: the state government and every county in Tennessee.
Nearby counties: Davidson County (20 mi) · Maury County (22 mi) · Rutherford County (27 mi) · Cheatham County (27 mi) · Marshall County (30 mi) · Dickson County (31 mi).