The county was created in 1820 and later organized in 1824. It is named for the Seneca Indians.
There are several mounds on the Culver Place from which time to time been plowed up by bones and ancient crockery. In 1850 one of these mounds was opened and in it was a large skeleton with a full shaped skull. And among other things a stone pitcher, which seems to have been made of sand and clay and smaller vessels filled with clam shells were found therein. These seemed as strange as the Indians as they did the whites.
- History of Seneca County, 1880, page 120.
- Historical Collections of Ohio, Volume 2, 1908, page 350 – 351.
- seneca county, seneca township source from Ross footnote 29 Henry Howe, LL.D. Published by the State of Ohio, 1900 (from 1888-1900)
- History of Seneca County, Ohio, 1911. “a large skeleton with a full shaped skull.”