The settling of Ohio began in 1788 with the arrival of 48 members of an expedition sponsored by the Ohio Company, a group that purchased more than one and a half million acres of the Northwest Territory by Congress. They chose what would become the city of Marietta as their first settlement.
The Ohio Company’s mission was helped along when General Anthony Wayne negotiated the Treaty of Greenville with the Native Americans in 1795. This treaty opened the door for settlement in much of the eastern and southern parts of the territory. Within three years, the male population of the area reached 5,000.
At that point, as provided for under the Northwest Ordinance of 1787, the settlers were given the right to elect a house of representatives. The first meeting of the legislature met in Cincinnati in 1799 and the body elected Edward Tiffin as Speaker of the House and William Henry Harrison as the territory’s representative to Congress.
The area that would soon be officially known as the State of Ohio continued to grow in population. In 1802, Congress passed a bill that authorized the formation of a state government in Ohio, and in 1803, Ohio was admitted to the Union as the 17th state.From "o HI' o Defined", published by the office of the Ohio Secretary of State