Where Does the Ohio River Start and End

In 1792, the government decided that it was Kentucky that owned the Ohio River and not the other bordering states of this valuable major trade route but ownership rights of the 3rd largest river by volume in the United States didn’t end there. Where does the Ohio River start and end?

The Ohio River is at the boundary of the Midwestern and Southern United States, flowing southwesterly 981 miles (1582 km) long, starting at the confluence of the Allegheny & the Monongahela Rivers in Pittsburgh, Pennsylvania, and ending in Cairo, Illinois, where it flows into the Mississippi River.

Technically, the river’s formation started between 2.5 and 3 million years ago, and that point marks the occurrence of the earliest ice ages. This is also when several portions of the north-flowing rivers were dammed thanks to the formation of ice, resulting in smaller rivers.

Where Does the Ohio River Start and End


 In the Hills of Pennsylvania, wet trails turn into brooks and streams so small they are hard to trace but all meet with each other to then turn into bigger streams and springs that eventually appear as a river.

These are headwaters of The Ohio River located near Coudersport, Pennsylvania.

The Allegheny River with its source in Allegheny Township in Pennsylvania joins a secondary source the Monongahela River at Fairmont, West Virginia.

The Allegheny River joins the Monongahela near Pittsburgh to form the Ohio River.

Elevation: 233m / 764feet

This is the famous Three Rivers of Pittsburgh where the Allegheny and Monongahela Rivers meet to form the Ohio River. The exact coordinates are N 40° 26.509 W 080° 00.785 


The Rivers in the United States that Source the Ohio River


  1. The Monongahela River runs 128 miles and is one of the few major navigable rivers in the world that run north. It starts at Fairmont, West Virginia, and flows north into Pennsylvania. Monongahela is derived from a Native American Word meaning “high banks or bluffs”
  2. The Allegheny River runs 325 miles from Porter County, PA into New York state, and back into Pennsylvania. The name comes from the Lenape Native Americans and is commonly believed to mean “fine river”.
  3. The Ohio River runs 981 miles ending at Cairo, IL, and is the largest tributary to the Mississippi River. The name comes from an Iroquoian word meaning “great river”.


The Ohio River is 981 miles (1582 km) long, starting at the confluence of the Allegheny and the Monongahela Rivers in Pittsburgh, Pennsylvania, and ending in Cairo, Illinois, where it flows into the Mississippi River.

Where Ohio joins the Mississippi is the lowest elevation in the state of Illinois, at 315 feet (96 m) The Ohio River flows through or borders six states: Illinois, Indiana, Kentucky, Ohio, Pennsylvania, and West Virginia.

The mouth of the Ohio River, where it empties into the Mississippi, is located in Cairo, Illinois at the spot where it meets Ballard County, Kentucky. Along the way, it has nearly a dozen tributaries that feed into the river.

These include the Kentucky River, the Tennessee River, the Cumberland River, the Great Miami River, the Kanawha River, and the Big Sandy River. From there these tributaries make up the watershed of the Ohio River which ends up running into the Mississippi and then draining into the Gulf of Mexico.


The Ohio River United States History


The Ohio River is rich in Native American history. For a thousand years, Native Americans used Ohio for transportation and trading with other communities along its path. The North American Osage, Omaha, Ponca, and Kaw peoples lived in the Ohio Valley.  Under pressure over the fur trade from the Iroquois nations to the northeast, they migrated west of the Mississippi River in the 17th century to the territory now defined as Missouri, Arkansas, and Oklahoma.

It is the third-largest river by discharge volume in the United States and the largest tributary by volume of the north-south flowing Mississippi River. Ohio is located in the eastern half of the US, dividing the mid-west and the southeast of the United States

It is also the 6th oldest river on the North American continent considered geologically as young.  During the Civil War, it served as the boundary between the Northern and Southern armies.

René-Robert Cavelier, Sieur de La Salle - Wikipedia René-Robert Cavelier, Sieur de La Salle, was a 17th-century French explorer and fur trader who was influential in the Seven Year War or The French and Indian War in North America, is said to have been the first European to see Ohio, in 1669, and he descended it until obstructed by a waterfall.

He also claimed the region watered by the Mississippi and its tributaries for France and named it Louisiana after King Louis XIV. His last expedition to establish fur trading posts failed and cost La Salle his life in 1687. By the treaty of 1763 ending the French and Indian Wars, the English finally gained undisputed control of the territory along its banks. 

In the 1750s the river’s strategic importance especially the fork at Pittsburgh in the struggle between the French and the English for possession of the interior of the continent became fully recognized.

During the 1800s, the Ohio River became an important commercial route for residents in Ohio, Kentucky, Indiana, and Illinois. Farmers and manufacturers sent their crops and finished products on flatboats and barges downstream to link up with the Mississippi River and then on to New Orleans.

Map of Ohio River Basin United States


Ohio River Valley Basin | DLZ


The Ohio River flows through or alongside six states: Illinois, Indiana, Kentucky, Ohio, Pennsylvania, and West Virginia. Water from parts of New York, Virginia, North Carolina, Tennessee, Maryland, Mississippi, Georgia, and Alabama drain into tributaries that empty into Ohio.

The Ohio River is the source of drinking water for more than five million people. More than 25 million people, almost 10% of the country’s population, live in the Ohio River Basin.

There are 20 dams on the Ohio River, managed by the Army Corps of Engineers. The dams have greatly altered the flow of the river, calming the currents down, creating slowing the river down, and creating deeper and slower-moving pools. These Dams raise the water levels and allow for commercial navigation up and down the river.

Industrial barges hauling steel and oil travel along the Ohio River creating commerce for the entire region. Slowing down the river by dams can influence water quality by settling some materials wouldn’t if the river was moving faster, resulting in lower turbidity.

The Army Corps of Engineers regularly dredge the river which some people feel is disrupting wildlife and adding more environmental concerns to the Ohio River Valley Basin.

Following floods at Johnstown, Pennsylvania, in 1889 and Portsmouth, Ohio, in 1937, the federal government built a series of flood-control dams not used for hydropower along the river flood control. The river has a total fall of 429 feet.

Because the Ohio River was considered a major trade route, border states decided they wanted a piece of the popular river. Soon, it would become a legal dispute with the government getting involved. In 1792, the government decided that it was Kentucky that owned the Ohio River along the state’s border with Ohio, Illinois, and Indiana. The reason behind this decision is that this boundary was the low point of the river’s northernmost bank but it didn’t end there.

About two centuries later, the State of Ohio sought to gain the claim to the Ohio River a second time. In 1966, the state made a point that the course of the river had fluctuated since 1792, making the aforementioned low point near the south bank of the river today. However, the United States Supreme Court didn’t change the legal ownership of the Ohio River, so it still belongs to Kentucky until this day.


Where does the Missouri River Start and End?

The Missouri River a tributary of the Mississippi starts in Three Forks, Montana, as the confluence of 3 major rivers, Madison, Jefferson & Gallatin & ends in St. Louis, Missouri. Crossing South Dakota, North Dakota, Nebraska, Iowa, Colorado, and Kansas, & at 2,540 mi. is the longest river in the US.………………………………………… Read more

What State Does the Ohio River End In


The Ohio Valley usually refers to the Ohio River Valley or the area that surrounds the legendary river. Some people will use the shorthand of the Ohio Valley to refer specifically to the upper part of the Ohio River Valley rather than the entire course of the River.

The Ohio River is the largest tributary of the Mississippi River, the Ohio River runs through six states and is 981 miles long. It begins in Pennsylvania and forms borders along Ohio, West Virginia, Indiana, Kentucky, and Illinois.

The Ohio River formed as a result of the flooding of a glacial lake in earlier ages. It connected two now-defunct rivers, the Steubenville River and the Amarietta River. This enlarged the previously small Marietta Valley.

Over the course of several Ice Ages, the Ohio River drained glacial lakes and was filled with flood waters from melting glaciers until it reached modern-era dimensions.  The Ohio River Valley drainage basin covered 205,000 square miles, which is equal to approximately 5% of the United States mainland.


Where does the Colorado River Start and End?

The Colorado River begins at La Poudre Pass in the Southern Rocky Mountains of Colorado, at 10,184 ft above sea level. After a short run south, it turns west below Grand Lake, then south at 1,450 mi. gaining strength from many tributaries to the Sea of Cortez in northwestern Mexico, where it ends..…………………………………………………… Read more


How Deep Is the Ohio River


The widest point along the Ohio River is approximately 1 mile at the Smithland Dam near Smithland, KY. The river has an average depth of approximately 24 feet deep. The Ohio River supports 160 species of fish.  There are 20 locks and dams on the Ohio River for flood control and navigation. There are 38 power-generating facilities on the Ohio River. 

The river’s deepest point is 168 feet (51 m) on the western side of Louisville Kentucky. From Louisville, the river loses depth very gradually until its confluence with the Mississippi at Cairo Illinois where it has an approximate depth of 19 feet (6 m). Velocities or how fast the water moves on the Ohio River can range from 0.1 mph under low flow to 5 mph at flood stage


Where Does the Hudson River Start and End?

The Hudson River headwaters start high in New York’s Adirondack Mountains near Mount Marcy sourced by Lake Tear & Opalescent River, Essex County runs southward 315 miles through Hudson Valley & Upper New York Bay between New York City & Jersey City emptying into .………………………………………………………………………… Read more



JimGalloway Author/Editor


References: History Channel-The Seven Year’s War

Biography-René-Robert Cavelier, Sieur de La Salle

Ohio River Valley Water Sanitation Commission



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