Seneca County, Ohio

Seneca County
Seneca County Justice Center in Tiffin, Ohio
Location within the U.S. state of Ohio
Ohio's location within the U.S.
Coordinates: 41°08′N 83°08′W / 41.13°N 83.13°W / 41.13; -83.13
Country United States
State Ohio
FoundedApril 1, 1824
Named afterthe Seneca nation
SeatTiffin
Largest cityTiffin
Area
  Total
553 sq mi (1,430 km2)
  Land551 sq mi (1,430 km2)
  Water1.8 sq mi (5 km2)  0.3%
Population
 (2020)
  Total
55,069
  Density100/sq mi (40/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional district5th
Websitesenecacountyohio.gov

Seneca County is a county located in the northwestern part of the U.S. state of Ohio. As of the 2020 census, the population was 55,069. Its county seat is Tiffin. The county was created in 1820 and organized in 1824. It is named for the Seneca Indians, the westernmost nation of the Iroquois Confederacy. This people were based in present-day New York but had territory extending into Pennsylvania and Ohio. Seneca County comprises the Tiffin, OH Micropolitan Statistical Area, which is also included in the Findlay–Tiffin, OH Combined Statistical Area.