Seneca

Formed April 1, 1820 (67^th county)

Seneca County (55,080), Tiffin (17,968)

The Modern red brick courthouse was constructed in 2018 to replace an 1886 building.  It is at Jefferson Street at Market Street.  Ohio State Highway 18 is Market Street in the town.  Gilbane and Silling are the architects.  The 2002 County Building sits next door.  The courthouse features a tower with a working clock.  There was also an 1822 wooden courthouse and an 1843 building.   The county was founded on April 1, 1820 from Huron County as the 67^th county with Tiffin as the only county seat.  Seneca County is named for the Native American tribe.  The county seat is named for Governor Edward Tiffin.  Seneca County is the birthplace of 1 Ohio Governor, Charles W. Foster, Jr. 

Seneca County government consists of a sheriff and 3 Commissioners.  Four Common Pleas Court Judges serve Seneca County.  Seneca County is in the northern part of Ohio.  Toledo, Ohio is northwest and Cleveland, Ohio is northeast of the county.  The county center is 2.7 miles East-Northeast of Tiffin.  The county is surrounded clockwise by Sandusky, Huron, Crawford, Wyandot, Hancock, and Wood counties. 

The area of the county is 550.6 square miles.  It is 16 out of 88 in the state.  It ranks 47 out of 88 in population in the state.  It has a density of 100.0 persons per square mile making it 55 out of 88 in the state.  Seneca County has 56.0% of its population in its incorporated areas.  United States Highway 23 follows the western border of the county with Wood County and goes south into Wyandot County.  United States Highway 224 crosses east to west from Huron County to Wood County.  The county is an overall rectangle.  Tiffin is located in the western third of the county.  Tiffin is the county seat and the largest city.  It is 32.6% of the county population.  The county is pronounced SEN-E-KA.  This county is in the Tiffin Micropolitan Statistical Area.