Ohio County Profiles Prepared by the Office of Research 2021 Edition Defiance County Named for: Fort Defiance Established: Act - April 7, 1845 2020 Population: 38,286 Land Area: 411.2 County Seat: Defiance City square miles Taxes Taxable value of real property $829,203,950 Residential $477,192,960 Agriculture $222,824,870 Industrial $29,488,130 ...