Formed 4 Mar 1845, 412 square miles
Parent counties: Williams, Henry, Paulding
Evolution of county from date of formation until it assumed its final form
7 Apr 1845: Erected and organized
County seat: Defiance
Federal Population schedules extant from 1820-1940. (1890 missing) In 1820, Defiance County was part of Wood County. The 1820 census for Wood County is missing.
1850 Agricultural; 1850 Industry; 1860 Agricultural; 1860 Mortality; 1870 Agricultural; 1870 Industry; 1880 Agricultural; 1880 Industry; 1880 Mortality
Adams, Defiance, Delaware, Farmer, Hicksville, Highland, Mark, Milford, Noble, Richland, Tiffin, and Washington.
Archival District: Bowling Green State University, Center for Archival Collections, Jerome Library, Bowling Green Ohio.Courthouse: 510 Court St., Defiance, OH 43512
Jana Broglin, OGSF