Ohio’s highest and lowest ground
The high point of Ohio is a hill in Logan County, not a mountain, and the state’s lowest ground is where the Ohio River leaves the state.
Ohio’s highest point is Campbell Hill, in Logan County near Bellefontaine. The United States Geological Survey lists Ohio’s high point as Campbell Hill in Logan County at an elevation of about 1,550 feet. Other reference sources give 1,549 feet; the difference is rounding rather than disagreement, and either figure makes the same point — Ohio’s summit is a hill on farmland in the middle of the state, not a peak.
The low point is at the other corner of the state, along the Ohio River in Hamilton County, in the south-west near Cincinnati, where the river forms Ohio’s southern boundary and leaves the state at its lowest elevation.
Between those two points Ohio is not uniform. Ohio History Central describes the state in terms of physiographic regions: the Central Lowlands, where Campbell Hill sits, and the glaciated and unglaciated ground that gives northern and southern Ohio their different character. The unglaciated south-east, in the Appalachian Plateau, holds the state’s steepest and most wooded terrain, which is why Ohio’s hill country is in the south-east while its flattest farmland is in the north-west.
The practical consequence for a traveller is that a statewide weather or road warning rarely applies evenly. Elevation across Ohio spans only about a thousand feet, but the landscape either side of the old glacial boundary behaves quite differently in snow and heavy rain.
See the USGS elevations table: https://www.usgs.gov/educational-resources/highest-and-lowest-elevations
Read about Ohio’s physiographic regions: https://ohiohistorycentral.org/w/Ohio%27s_Physiographic_Regions