When the war was over and these cessions had been made a great number of war veterans wished an opportunity to repair their broken fortunes in the West, and Congress, hopeful of receiving a large revenue from the sale of lands here, passed an ordinance on the 20th of May 1785 by which the present national system of land-surveys into townships 6 m. sq. was inaugurated in what is now S.W. Ohio in the summer of 1786. In March 1786 the second Ohio Company (q.v.), composed chiefly of New England officers and soldiers, was organized in Boston, Massachusetts, with a view to founding a new state between Lake Erie and the Ohio river. The famous North-West Ordinance was passed by Congress on the 13th of July 1787. This instrument provided a temporary government for the Territory with the understanding that, as soon as the population was sufficient, the representative system should be adopted, and later that states should be formed and admitted into the Union. There were to be not less than three nor more than five states. Of these the easternmost (Ohio) was to be bounded on the N., E. and S. by the Lakes, Pennsylvania and the Ohio river, and on the W. by a line drawn due N. from the mouth of the Great Miami river to the Canadian boundary, if there were to be three states, or to its intersection with an E. and W. line drawn through the extreme S. bend of Lake Michigan, if there were to be five. Slavery was forbidden by the sixth article of the ordinance; and the third article read: “Religion, morality and knowledge being necessary to good government and the happiness of mankind, schools and the means of education shall for ever be encouraged.” After the adoption of the North-West Ordinance the work of settlement made rapid progress. There were four main centres. The Ohio Company founded Marietta at the mouth of the Muskingum in 1788, and this is regarded as the oldest permanent settlement in the state. An association of New Jerseymen, organized by John Cleves Symmes, secured a grant from Congress in 1788–1792 to a strip of 248,540 acres on the Ohio between the Great Miami and the Little Miami, which came to be known as the Symmes Purchase. Their chief settlements were Columbia (1788) and Cincinnati (1789). The Virginia Military District, between the Scioto and the Little Miami, reserved in 1784 for bounties to Virginia continental troops, was colonized in large measure by people from that state. Their chief towns were Massieville or Manchester (1790) and Chillicothe (1796). A small company of Connecticut people under Moses Cleaveland founded Cleveland in 1796 and Youngstown was begun a few years later, but that portion of the state made very slow progress until after the opening of the Ohio & Erie Canal in 1832.
During the Territorial period (1787–1803) Ohio was first a part of the unorganized North-West Territory (1787–1799), then a part of the organized North-West Territory (1799–1800), and then the organized North-West Territory (1800–1803), Indiana Territory having been detached from it on the W. in 1800. The first Territorial government was established at Marietta in October 1787, and General Arthur St Clair (1734–1818), the governor, arrived in the summer of 1788. His administration was characterized by the final struggle with the Indians and by a bitter conflict between the executive and the legislature, which greatly influenced the constitutional history of the state. The War of Independence was succeeded by a series of Indian uprisings. Two campaigns, the first under General Josiah Harmar (1753–1813) in 1790, and the second under General St Clair in 1791, failed on account of bad management and ignorance of Indian methods of warfare, and in 1793 General Anthony Wayne (q.v.) was sent out in command of a large force of regulars and volunteers. The decisive conflict, fought on the 20th of August 1794, near the rapids of the Maumee, is called the battle of Fallen Timbers, because the Indians concealed themselves behind the trunks of trees which had been felled by a storm. Wayne’s dragoons broke through the brushwood, attacked the left flank of the Indians and soon put them to flight. In the treaty of Greenville (3rd August 1795) the Indians ceded their claims to the territory E. and S. of the Cuyahoga, the Tuscarawas, and an irregular line from Fort Laurens (Bolivar) in Tuscarawas county to Fort Recovery in Mercer county, practically the whole E. and S. Ohio. The Jay Treaty was ratified in the same year, and in 1796 the British finally evacuated Detroit and the Maumee and Sandusky forts. By cessions and purchases in 1804, 1808 and 1817–1818 the state secured all of the lands of the Indians except their immediate homes, and these were finally exchanged for territory W. of the Mississippi. The last remnant migrated in 1841. General Wayne’s victory was followed by an extensive immigration of New Englanders, of Germans, Scotch-Irish and Quakers from Pennsylvania, and of settlers from Virginia and Kentucky, many of whom came to escape the evils of slavery. This rapid increase of population led to the establishment of the organized Territorial government in 1799, to the restriction of that government in Ohio in 1800, and to the admission of the state into the Union in 1803.
The Congressional Enabling Act of the 30th of April 1802 followed that alternative of the North-West Ordinance which provided for five states in determining the boundaries, and in consequence the Indiana and Michigan districts were detached. A rigid adherence to the boundary authorized in 1787, however, would have resulted in the loss to Ohio of 470 sq. m. of territory in the N.W. part of the state, including the lake port of Toledo. After a long and bitter dispute—the Toledo War (see Toledo)—the present line, which is several miles N. of the S. bend of Lake Michigan, was definitely fixed in 1837, when Michigan came into the Union. (For the settlement of the eastern boundary, see Pennsylvania.)
After having been temporarily at Marietta, Cincinnati, Chillicothe and Zanesville the capital was established at Columbus in 1816.
Since Congress did not pass any formal act of admission there has been some controversy as to when Ohio became a state. The Enabling Act was passed on the 30th of April 1802, the first state legislature met on the 1st of March 1803, the Territorial judges gave up their offices on the 15th of April 1803, and the Federal senators and representatives took their seats in Congress on the 17th of October 1803. Congress decided in 1806 in connexion with the payment of salaries to Territorial officials that the 1st of March 1803 was the date when state government began. During the War of 1812 the Indians under the lead of Tecumseh were again on the side of the British. Battles were fought at Fort Meigs (1813) and Fort Stephenson (Fremont, 1813) and Commodore Oliver Hazard Perry’s naval victory on Lake Erie in 1813 was on the Ohio side of the boundary line.
Owing to the prohibition of slavery the vast majority of the early immigrants to Ohio came from the North, but, until the Mexican War forced the slavery question into the foreground, the Democrats usually controlled the state, because the principles of that party were more in harmony with frontier ideas of equality. The Whigs were successful in the presidential elections of 1836 and 1840, partly because of the financial panic and partly because their candidate, William Henry Harrison, was a “favourite son,” and in the election of 1844, because of the unpopularity of the Texas issue. Victory was with the Democrats in 1848 and 1852, but since the organization of the Republican party in 1854 the state has uniformly given to the Republican presidential candidates its electoral votes. In the Civil War Ohio loyally supported the Union, furnishing 319,659 men for the army. Dissatisfaction with the President’s emancipation programme resulted in the election of a Democratic Congressional delegation in 1862, but the tide turned again after Gettysburg and Vicksburg; Clement L. Vallandigham, the Democratic leader, was deported from the state by military order, and the Republicans were successful in the elections of 1863 and 1864. A detachment of the Confederate cavalry under General John Morgan invaded the state in 1863, but was badly defeated in the battle of Buffington’s Island (July 18th). Democratic governors were elected in 1873, 1877, 1883, 1889, 1905, 1908 and 1910. Five presidents have come from Ohio, William Henry Harrison, Rutherford B. Hayes. James A. Garfield, William McKinley, Jr., and William Howard Taft.