6 Oldest Rivers In The United States

Although the United States is young for a country, the landmass itself is very old. As a result, some of the oldest rivers in the world are found in this nation. Knowing this, we have to ask some questions. For example, how can we tell how old a river is? What are the oldest rivers in the United States? We’re going to take a close look at the nature of rivers and answer both of those questions by showing you six exceptionally old rivers in the United States.

What Is A River?

Rivers are bodies of water with specific properties. For example, rivers are moving bodies of water that flow from one area to an outlet, usually into a larger body of water. They are not landlocked, but they are bound by their riverbanks. Most rivers are completely freshwater, but some have a high amount of salinity, especially those that have outlets in the sea or oceans.  

The world is home to hundreds of major rivers and many more small ones. Even though some of these rivers are massive, they only account for 0.49% of all surface freshwater!

Determining the Age of the Oldest Rivers in the United States

How can we say with any certainty the age of the oldest rivers in the United States? The truth is that determining the ages of rivers requires educated guesswork instead of a specific form of measurement. Scientists look at geological disturbances that have taken place in the rivers’ areas over time.

They can determine with some certainty the era in which the river came into being according to the slow-moving geological processes at work. Since rivers often form in valleys between rivers, the river’s age can be deduced by examining the age of the mountain-forming events and other geological activity in the area.

As we look farther back in time, the certainty of the river’s specific age begins to wane. Humans don’t have a precise timeline for all these historical events. As you will see on this list, many of the estimated formation times vary by tens of millions of years for this reason.

Now that you know how scientists come up with the ages of a river, we can start to look at the oldest rivers in the United States.  

The 6 Oldest Rivers in the United States

As said earlier, the United States is home to some of the oldest rivers in the world. Several of them are hundreds of millions of years in age. Others are much newer, and some are very difficult to age correctly. Let’s take a look at the six oldest rivers in the United States and show their ages!

6. Ohio River: 2.5-3 Million Years Ago

The Ohio River is believed to have formed somewhere between 2.5 and 3 million years ago. The cause of this river’s formation was the damming of the Teays River by the Laurentide Ice Sheet. The river water from the Teays River could no longer reach its outflow, so it began to drain to the south and eventually formed this river.

The Ohio River’s outflow is the Mississippi River, another vast river network in the United States.  

5. Columbia River: 6-17 Million Years Old

The Columbia River is between 6 and 17 million years old, and it flows from parts of Canada through the state of Washington and then some of Oregon before reaching its outlet in the Pacific Ocean. The Columbia River was formed through a significant volcanic activity that impacted the Pacific Northwest.

Eventually, the Columbia Plateau was altered to such a great extent that the Columbia River took on its present course.  

4. Colorado River: 75 Million Years Old

The Colorado River is one of the largest rivers in the United States and the fourth oldest. This river is most famous for running through the Grand Canyon, and it was formed during the Laramide orogeny, the same event that created the Rocky Mountains. Another great landmark along the Colorado River, albeit manmade, is the Hoover Dam in Nevada. It was built in 1931 not only to supply power, but also to prevent flooding in the Southwest caused by the river.

Fortunately, the geological transformations in the area left a great deal of evidence as to the era in which they were created. As a result, the age of this river is somewhat more fixed than others. The Colorado River is also comparable in age to the Nile River in Egypt and the Murrumbidgee River in Australia.  

3. French Broad River: 320-340 Million Years Old

The French Broad River could potentially be the oldest of all the rivers in the United States, but some evidence suggests it was created closer to the 320 million years ago mark than the 340 million years ago mark.

Interestingly, the French Broad River, Susquehanna River, and New River all run through the same mountain range, the Appalachian Mountains, but in different areas. The French Broad River eventually drains into the Tennessee River.  

2. Susquehanna River: 260-325 Million Years Old

The Susquehanna River is roughly the same age as the New River, somewhere between 260 and 325 million years old. This river was formed during the same geological event that made the French Broad River and the New River.

The Susquehanna River is a very long river. Eventually, it lets out into the Chesapeake Bay after traveling through New York, Pennsylvania, and Maryland.

1. New River: 260-325 Million Years Old

The New River is the oldest river in the United States. However, as you can see from the top three oldest rivers in the country, the New River could very well be older or newer than the Susquehanna River and the French Broad River.

Nevertheless, most experts agree that the New River is the oldest in the nation, and it was developed during the Alleghenian orogeny. That puts the river at somewhere between 260 million years of age and 325 million years of age. This is a very old river, and it’s believed to be the third oldest river in the world.

The United States is home to many large river systems and several old ones, too. The geology in this part of the world is noteworthy and often beautiful. Now that we know some of the oldest lakes in the United States, we can see that the rivers run the gamut in age. From 325 million years to less than 3 million years, this area has rivers of all ages!

Honorable Mention: The Mississippi River

While it didn’t make our top 6 list, the mighty Mississippi River qualifies as one of the oldest in the United States. The general consensus has been that it was formed during the Pre-Illinoian glaciation when the Laurentide Ice Sheet dammed the Teays River. As that river could no longer drain to the north, it redirected southwards, forming the Ohio River, as we explored earlier.

During that same time, the southernmost area of the glaciation extended into what is now the Mississippi basin. As the ice receded, the Mississippi Valley was left, containing hundreds of feet of sediment deposits. Glacial melting created the rivers in the Mississippi watershed, including the James River, Minnesota River, and Milk River. While these rivers made their way to the Hudson Bay or Arctic Ocean, the Mississippi pushed south to the Gulf of Mexico.

There is conflicting data on how old the Mississippi River is, and new discoveries are always being made. As recently as 2020, the Smithsonian Magazine put out an article stating that a conservative estimate on the age of the Mississippi River is 70 million years, making it older than both the Ohio River and Columbia River.

The 6 Oldest Rivers in the United States vs. the World

Do any of the oldest rivers in the United States make the list of the top 10 oldest rivers in the world? Let’s find out:

1. Finke River: Australia, 350-400 million years old
2. Meuse River: Europe, 320-340 million years old
3. French Broad River: United States, 320-340 million years old
4. New River: United States, 260-325 million years old
5. Susquehanna River: United States, 260-325 million years old
6. Rhine River: Europe, 240 million years old
7. Save River: Europe, 205 million years old
8. Amur River: Zimbabwe & Mozambique, 125 million years old
9. Macleay River: Australia, 80 million years old
10. Colorado River: United States, 75 million years old

Summary Of The 6 Oldest Rivers In The United States

To recap, here are the 6 oldest rivers in the US and their ages: