54,730 people (2024 Census estimate, −0.6% since 2020)
551 square miles of land · 99 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.
11 active community water systems list Seneca County in the area they serve, reporting 39,207 people served in all (a system that crosses county lines counts its whole population).
| AQUA OHIO - TIFFIN surface water · private · OH7400614 | 20,279 served |
| FOSTORIA CITY surface water · local government · OH7400411 | 13,441 served |
| GREEN SPRINGS VILLAGE PWS buys surface water · local government · OH7400512 | 1,592 served |
| ATTICA VILLAGE surface water · local government · OH7400011 | 1,148 served |
| BLOOMVILLE VILLAGE PWS groundwater · local government · OH7400212 | 956 served |
| BETTSVILLE VILLAGE groundwater · local government · OH7400112 | 692 served |
| REPUBLIC VILLAGE groundwater · local government · OH7400812 | 550 served |
| FOSTORIA MOBILE ESTATES groundwater · private · OH7400712 | 281 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 165 people were held in Seneca County's jail, in Vera's latest figure (2023), or 480 per 100,000 residents ages 15–64. In 2018 it was about 204.
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.
5 school districts have their office in Seneca County. School taxes are usually the largest part of a property tax bill.
Spent $38.1 million — $33 million to run schools, about $12,727 per student, plus $1.5 million on buildings and equipment. Money in: $17.6 million local (mostly property tax), $14.9 million state, $3.7 million federal. Long-term debt: $2.2 million.
Spent $15.2 million — $12.9 million to run schools, about $15,249 per student, plus $864,000 on buildings and equipment. Money in: $7 million local (mostly property tax), $6.2 million state, $1.1 million federal. Long-term debt: $7.5 million.
Spent $12.3 million — $9.7 million to run schools, about $12,501 per student, plus $1.3 million on buildings and equipment. Money in: $7.7 million local (mostly property tax), $4.4 million state, $1.9 million federal. Long-term debt: $11.7 million.
Spent $13 million — $10.1 million to run schools, about $13,587 per student, plus $2.7 million on buildings and equipment. Money in: $4.7 million local (mostly property tax), $5.3 million state, $1.6 million federal. Long-term debt: $85,000.
Spent $6.4 million — $6.1 million to run schools, about $13,734 per student, plus $187,000 on buildings and equipment. Money in: $2.9 million local (mostly property tax), $3.6 million state, $408,000 federal. Long-term debt: $3.5 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 Low compared with other U.S. counties. FEMA estimates natural hazards cost Seneca County about $16.2 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.
278 bridges in Seneca County: 205 in good condition, 69 fair, and 4 poor (1.4%). “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.
| RIVER RD. over WILLOW CREEK · built 1914 | 1,701 vehicles a day |
| PLE CR 62 over GREEN CREEK PL · built 1978 | 831 vehicles a day |
| BLO TR 77 over HONEY CREEK · built 1943 | 155 vehicles a day |
| PLE TR 143 over SANDUSKY RIVER "CLOSED" · built 1914 | 0 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $15.4 million of work in Seneca County in fiscal 2025, about $280 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 Ohio 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 Seneca 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 Seneca County built: brayden.ozark@gmail.com.
More of Ohio: the state government and every county in Ohio.
Nearby counties: Sandusky County (16 mi) · Crawford County (21 mi) · Wyandot County (22 mi) · Huron County (28 mi) · Hancock County (29 mi) · Ottawa County (30 mi).