Ohio /oʊˈhaɪ.oʊ/ is a state in the Midwestern United States. Ohio is the 34th largest (by area) , the 7th most populous, and the 10th most densely populated of the 50 United States. The state's capital and largest city is Columbus.The state takes its name from the Ohio River.The name originated from the Iroquois word ohi-yo’ , meaning great river or large creek.hio's population growth lags that of the entire United States, and Caucasians are found in a greater density than the United States average. As of 2000, Ohio's center of population is located in Morrow County, in the county seat of Mount Gilead.