Ohio Country great river Indians mound builders The history of Ohio as a state began when the Northwest Territory was divided in 1800 and remainder reorganized for admission to union on March 1 1803 17th United States. recorded late century French explorers from Canada reached River which took its name river Iroquois called O-y-o . Before that Native Americans speaking Algonquin languages had inhabited central midwestern States hundreds years until displaced by latter part century. Other cultures not generally identified including Hopewell preceded them. Human few millennia after formation Bering land bridge about 14500 BCE – see Prehistory Ohio. By mid-18th century American fur traders engaged historic tribes present-day trade. their own extensive trading networks across continent before Europeans arrived. settlement Country came Revolutionary War States with takeover former British Canadian territory. Congress prohibited slavery presaged five states entering Union free states. Ohio's population increased rapidly victory Indian Wars brought peace frontier. On admitted state. Settlement chiefly migrants New England York Pennsylvania. Southerners settled along southern territory arriving travel River Upper South. Yankees especially "Western reserve" (near Cleveland) supported modernization public education anti-slavery policies. Civil War although antiwar Copperhead sentiment strong areas.