Why Is It Near Impossible to Determine the Longest River on Earth?

Do you know what is the longest river in the world? If you don't, you're not alone. People hesitate between the Nile river in Africa, the Amazon river in South America, the Yangtze river in Asia, and the Mississippi river in North America.

Even the internet seems to be confused. Wikipedia, NASA, and the Guinness World Record all say that the Nile is the longest river while Google and the History Channel point to the Amazon. Why the confusion?

Because rivers are notoriously hard to measure. Take the Mississippi river for instance. It has the Jefferson river and the Missouri river that both lead to it. If you consider these two rivers as part of the Mississippi river then you triple its length. But are they part of the Mississippi river? How is it that in the 21st Century we still don't have a way to measure rivers precisely?

Well, it's partially because rivers also change their course over time. What needs to be considered when measuring a river's length? How can we get more precise measures? And what is truly the world's longest river? This video explores all these questions and comes as close as possible to answering them.