Ross County, Ohio: History
Ross County was formed by proclamation of Governor St. Clair, August 20, 1798, being the sixth county formed in the Northwest Territory.
Ross County was described by Ephraim George Squier and Edwin Hamilton Davis as having almost "one hundred enclosures of various sizes, and five hundred mounds" in their book, Ancient Monuments of the Mississippi Valley (1848). They described the Indian-built earthworks as ranging from 5 to 30 feet (1.5–9.1 m) in size, and enclosures of 1 to 50 acres (0.40–20.23 ha) large. These included Serpent Mound, Fort Ancient, Mound City, and Seip Earthworks (both now part of Hopewell Culture National Historical Park), and Newark Earthworks.