Ohio was the third township to be formed in Allegheny county north of the Ohio river, and the first subdivision of Pine township. Its erection was agitated in December, 1802, when a petition was filed in the court of quarter sessions, representing that Pine extended twenty-three miles along the Ohio and Allegheny rivers, adjoining Butler and Beaver counties. The line of Nicholson’s and Douglass’ districts was suggested as the line of division, the western portion to include Neville’s island and be called Ohio township. Gen. John Neville signed this petition. At the June sessions, 1803, a division was petitioned for by the Jack’s ferry and Franklin roads. At this time there were but forty-seven miles of road in the whole of Pine township. It was averred that if the eastern boundary of Nicholson’s district were made the line of division, thirteen miles of road would be included in the portion east of that line, and thirty-four miles in the portion west of it; but if the Franklin road were made the dividing line, the eastern division would include twenty-seven miles of road and the western division twenty. It was thought that the roads should be apportioned as equally as possible, as their repair was imposed upon each township separately; but it was also urged that the roads were an advantage to the territory they traversed, and that consideration seems to have contributed but little to the final result. At the September term, 1803, the court confirmed absolutely a division by the line of Nicholson’s and Douglass’ districts, erecting the territory west of that line into Ohio township. It then included in addition to its present area the townships of Marshall, Franklin, Sewickley, Leet, Kilbuck and Aleppo.

The taxable inhabitants of this territory in 1814 were as follows:
Philip Brown, Benjamin Butler, Henry Cresse, Patrick Brown, Patrick Bolao, William Courtney, James Brannon, John Belwood, Isaac Craig,Robert Baldwin, Thomas Backhouse,
Benjamin Dilworth, Peter Bonham, William Backhouse, Alexander Duff, Elias Brener, Francis Boggs, David Duff, John Been, John Bolan, David Duff (miller), Zachariah Bonham,
Moses Cox, James Duff, Jr., Addy Beer, John Crill, William Duff, Jacob Brower, John Culbertson, James Duff, Sr., John Brower, Andrew Cresse, Hugh Duff, Michael Benin,
William Cox, William Dixon, Right Brewer, John Cresse, Sr., David Dixon, Archibald Boyd, John Cresse, Jr., Joseph Dickson, Rosanna Brocooner, George Cresse, John Dickson,
Robert Boyd, Samuel Cresse, Nancy Dunning, Andrew Emerigh, Matthew Ingram, Samuel Moore, David Eakins, William Ingram, William McLaughlin, Jesse Fisher, James Jones,
Samuel Merriman, Sr., John Frampton, John Jackson, Ellis Moore, David Flones, Charles Jones, Eli Moore, John Fouser, William Jones, Allen Mans, Jacob Fry, Barney Jackman,
Thomas Mans, John Fowler, Hugh Luster, John Moore, William Fowler, William Larrimore, John McMorton, John Gilland, Daniel Leet, Daniel Malson, Samuel Gunsaul, Abraham Larrimore,
William McDonald, Hans Greer, Matthew Logan, John Means, John Gibson, John Little, Thomas McClelland, Robert Gibson, Robert Linn, James Neely, Gideon Gibson, Jacob Long, Samuel Neely,
Nicholas Grossman, John Mitchell, John Neely, William Grossman, Moses Modie, Sylvester Needham Andrew Gilland, John Moore, William Oliver, Benjamin Gunsaul, Zechariah McPherson,
John Oliver, Meshach Holt (negro), Nathan McPherson, Martin Oliver, Elizabeth Hamilton, John McCreary, George Oliver, William Hamilton, Richard Merriman, Samuel Oliver, David Hamilton,
Frederick Merriman, Thomas Oliver, Charles Hamilton, William Moore, James Owens, Thomas Holmes, Sr., Jane Moore, Eleanor Pearce, Joseph Holmes, James Moore, Sr., Amos Pearce, McClelland Hood,
Lewis Moore, Andrew Pinkerton, Eleanor Pearce, Abraham Ritchey, John Snider, John Pinkerton, Isaac Ritchey, Giles Stephens, John Phrazor, William Ritchey, Philip Snyder, James Park,
Jacob Ritchey, John Scott, Robert Quaile, Abraham Ritchey, Sr., John Smith, Robert Rowland, George Shannon, James Scott, Sr., William Rowland, William Riley, Robert Scott, Margaret Right,
Abel Starr, William Sutton, James Robinson, William Simms, Adam Scott, Jacob Sewer, George Shannon, John Way Edward Sharp, George Shearer, William Wilkins, Isaac Skiles, William Trineary,
James Wilkins, William Skiles, John Taylor John Wright, James Skiles, Henry Ullery, Thomas Waggoner, Felix Sigler, George Ullery, John White, Henry Shrum, James Updegraff, Andrew White, Philip Young, John Young, Thomas Young.

Practically, Ohio has been reduced to its present limits by the erection of Franklin in 1823, Sewickley in 1854, and Kilbuck in 1869. No event of remarkable interest signalized its early settlement. Being situated on the "Indian side" of the river, the first white inhabitants did not appear more than a few years prior to 1800, as this section of country was not open to settlement until 1792. Henry Wilson, a squatter, is said to have been the first settler. Of William Richey, who settled permanently in 1801, the following story is told: "He had been a soldier in Wayne’s expedition. While the army was lying at Legionville, he was sent on some commission to Fort Pitt. When a short distance from camp he heard a wild turkey gobble near by. The sounds were repeated, and he followed them, but cautiously and behind the trees. At length, upon exposing a part of his body, he observed an Indian in the act of taking aim at him over a clump of bushes. He was standing on tiptoe to obtain a fair view, but Richey was too quick for him, and before the savage could fire he planted a bullet between his eyes. He then took his gun and tomahawk, hid them in a hollow tree, and went on. Years afterward he returned to the place and found the gun where he had left it; the barrel is still in possession of one of the family." The Duff family was first represented by James Duff and his two sons, who crossed the Ohio river in 1799 and located near that stream, removing farther inland in 1805. James Moore immigrated from Northumberland county with a large family about the same time. He owned a large tract of land.

In addition to these, the Crawfords, who settled on Lowrie’s run, and have been numerously represented by their descendants, the Gillilands, the Ritchies, Shannons and others are remembered.

Ohio is an agricultural township. Its farms and forests constitute its only resources. Within a recent time search has been prosecuted for oil, and gas has been discovered, though not in such quantities as in some other fields. There are in the township no manufactories and no villages. The population is sparse. In 1860 it was 1,350; in 1870, 685; in 1880, 737. There are two election precincts. The principal streams are Kilbuck run and Lowrie’ s run.

Methodism was introduced into the township by Rev. Thomas McClelland, a local preacher, who became a resident of Sewickley valley in 1808 or 1809. In 1811, through John Way, Sr., Mr. McClelland, Matthew Ingram and Charles Hamilton purchased farms some distance inland from the river, and removed thither. He organized a Methodist society at his own home, which was also the place of worship. He also organized a class at the home of Mrs. Elizabeth Frazier. The place of preaching was removed to the schoolhouse on the farm of Jacob Fry some years later, and subsequently to the residence of Thomas Hamilton. A log church-building was erected on his farm prior to 1834, upon the site of the present "Blackburn chapel."

Mount Nebo United Presbyterian Church was organized in 1838. A church building was erected two years later. The pastors have been as follows: W. Burnett, 1845-50; J. Greer, 1852-55; J. L. Fairley, 1856-69; D. R. Imbrie, 1870-72; W. J. Cooper, 1874-77; D. R. Imbrie, 1878-. The first schoolhouse was built in 1806, in the western part of the township. Four schools are sustained at this time.