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O·hi·o(ō-hī′ō) Abbr. OH or O.
A state of the north-central United States south of Lake Erie. It was admitted as the 17th state in 1803. In prehistoric times Mound Builders inhabited the region, which was explored by La Salle in 1669. The French-British rivalry for control of the area led to the last of the French and Indian Wars (1754-1763), in which the French were defeated. Ohio was part of the vast area ceded to the United States by the Treaty of Paris in 1783 and became part of the Northwest Territory by the Ordinance of 1787. It became a separate territory in 1799. Columbus is the capital.