Much of Ohio features glaciated plains, with an exceptionally flat area in the northwest being known as the Great Black Swamp. This glaciated region in the northwest and central state is bordered to the east and southeast first by a belt known as the glaciated Allegheny Plateau, and then by another belt known as the unglaciated Allegheny Plateau. Most of Ohio is of low relief, but the unglaciated Allegheny Plateau features rugged hills and forests.

The rugged southeastern quadrant of Ohio, stretching in an outward bow-like arc along the Ohio River from the West Virginia Panhandle to the outskirts of Cincinnati, forms a distinct socio-economic unit. Known somewhat erroneously as Ohio's "Appalachian Counties" (they are actually in the Allegheny Plateau), this area's coal mining legacy, dependence on small pockets of old manufacturing establishments, and even distinctive regional dialect set this section off from the rest of the state and, unfortunately, create a limited opportunity to participate in the generally high economic standards of Ohio.

The indigenous nations to inhabit Ohio in the historical period (most clearly after 1700), included the Miamis (a large confederation), Wyandots (made up of refugees, especially from the fractured Huron confederacy), Delawares (pushed west from their historic homeland in New Jersey), Shawnees (also pushed west, although they may be descended from the Fort Ancient people of Ohio), Ottawas (more commonly associated with the upper Great Lakes region), Mingos (like the Wyandot, a recently-formed composite of refugees from Iroquois and other societies) and Eries (gradually absorbed into the new, multi-ethnic "republics," namely the Wyandot).

During the 18th century, the French set up a system of trading posts to control the fur trade in the region. In 1754, France and Great Britain fought a war known in the United States as the French and Indian War. As a result of the Treaty of Paris, the French ceded control of Ohio and the rest of the Old Northwest to Great Britain. Pontiac's Rebellion in the 1760s challenged British military control, which ended with the American victory in the American Revolution. In the Treaty of Paris in 1783 Britain ceded all claims to Ohio to the United States.

The United States created the Northwest Territory under the Northwest Ordinance of 1787. Slavery was not permitted. Settlement began with the founding of Marietta by the Ohio Company of Associates, which had been formed by a group of American Revolutionary War veterans. Following the Ohio Company, the Miami Company (also referred to as the "Symmes Purchase") claimed the southwestern section and the Connecticut Land Company surveyed and settled the Connecticut Western Reserve in present-day Northeast Ohio. The old Northwest Territory originally included areas that had previously been known as Ohio Country and Illinois Country. As Ohio prepared for statehood, Indiana Territory was created, reducing the Northwest Territory to approximately the size of present-day Ohio plus the eastern half of the Lower Peninsula of Michigan and the eastern tip of the Upper Peninsula.

In 1835, Ohio fought a mostly bloodless boundary war with Michigan over the Toledo Strip known as the Toledo War. Congress intervened and, as a condition for admittance as a state of the Union, Michigan was forced to accept the western two-thirds of the Upper Peninsula, in addition to the eastern third that was already part of the state, in exchange for giving up its claim to the Toledo Strip. (A war between two states may be unusual, but the Toledo War is not unique; Pennsylvania and Maryland fought Cresap's War over a border dispute a century earlier.) Ohio's central position and its population gave it an important place during the Civil War, and the Ohio River was a vital artery for troop and supply movements, as were Ohio's railroads.

The executive branch of Ohio government comprises six officers elected statewide for four-year terms, all on a partisan ballot - Governor and lieutenant governor, elected jointly on a single ticket. The governor appoints a cabinet whose members direct a number of state regulatory agencies - Secretary of State, Attorney General, Auditor and Treasurer.

The legislative branch, the Ohio General Assembly, is made up of two houses--the senate and the house of representatives. The house of representatives is composed of 99 members elected from single-member districts of equal population. Each of the 33 senate districts is formed by combining three house districts. Senators serve four-year staggered terms and representatives serve two-year terms. In order to be enacted into law, a bill must be adopted by both houses of the assembly and signed by the governor. If the governor vetoes a bill, the assembly can override the veto with a three-fifths supermajority of both houses. A bill will also become a law if the governor fails to sign or veto it within 10 days of its being presented. The Legislative Service Commission is one of several legislative agencies. It serves as a source for legal expertise and staffing. The commission drafts proposed legislation.

The judicial branch is headed by the supreme court, which has one chief justice and six associate justices, each elected to staggered six-year terms. There are several other levels of elected judiciary in the Ohio court system.They are:

State court of claims, which has jurisdiction over all civil actions against the State of Ohio in situations in which the state has waived its sovereign immunity. State courts of appeal (12 district appeals courts): These are the intermediate appellate courts. County courts of common pleas: 88 county common pleas courts -- These are the principal courts of first instance for civil and criminal matters. In populous areas, there are often several divisions, such as general, juvenile, probate, and domestic relations. Municipal courts and county courts -- these court primarily handle minor matters, such as traffic adjudication and other misdemeanor and small claims. Judges in Ohio are generally elected, except for the Court of Claims, for which judges sit by assignment of the chief justice. When there are temporary vacancies in elected judgeships, those vacancies are also filled by assignment by the chief justice.

Ohio is the site of the invention of the airplane, resulting from the experiments of the Wright brothers in Dayton. Production of aircraft in the USA is now centered elsewhere, but a large experimental and design facility, Wright-Patterson Air Force Base has been located near Dayton and serves in the co-ordination of production of US military aircraft. On the base are located Wright Hill and Huffman Prairie, where many of the earliest aerodynamic experiments of the Wright brothers were performed. Ohio today also has many aerospace, defense, and NASA parts and systems suppliers scattered throughout the state.

As part of the Corn Belt, agriculture also plays an important role in the state's economy. There is also a small commercial fishing sector on Lake Erie, and the principal catch is yellow perch. In addition, Ohio's historical attractions, varying landscapes, and recreational opportunities are the basis for a thriving tourist industry. Over 2,500 lakes and 43,000 miles (70,000 km) of river landscapes are a paradise for boaters, fishermen, and swimmers. Three major amusement parks, Cedar Point, Geauga Lake, and Paramount's Kings Island, are also important to the tourism industry. Of special historical interest are the Native American archaeological sites—including grave mounds and other sites.

The Bureau of Economic Analysis estimates that Ohio's gross state product in 2004 was $419 billion. Per capita personal income in 2003 was $30,129, 25th in the nation. Ohio's agricultural outputs are soybeans, dairy products, corn, tomatoes, hogs, cattle, poultry and eggs. Its industrial outputs are transportation equipment, fabricated metal products, machinery, food processing, and electricity equipment.