Because early peoples depended on rivers for survival, they were among the first geological features to receive official names. Many of the origins are so old, in fact, that they're lost to history. Here's what we do know.

MISSISSIPPI



(Image credit: Flickr user Prayitno)

Description: The U.S.'s second-longest river (after the Missouri) begins at Lake Itasca in Minnesota and travels 2,340 miles south, all the way to the Gulf of Mexico.

Origin: The name is believed to be a combination of two Indian words, although experts aren't sure which ones. It may have been the Ottawa mici ("great") and zibi ("river"), or the Algonquin misi ("father") and sipi ("water"). What is certain is that in 1666 French explorers in the Great Lakes region recorded it as Messippi. As they traveled south, that name supplanted all of the other names in use. In 1798 the U.S. Congress officially named the new territory after the Algonquin version, "Mississippi."

NILE



Description: The Nile is actually two rivers -the White Nile and the Blue Nile- that join up in Sudan before flowing north across Egypt and into the Mediterranean. In all, the world's longest river system travels 4,100 miles through ten African nations.

Origin: Because many different cultures have lived along the Nile's banks for at least 5,000 years, this river has gone by many names: Iteru ("River of Life"), Ar ("Black," due to the black sediment left behind after the annual floods), and Nahal ("Valley"). When the ancient Greeks traveled to the region, they called it Nelios, meaning "River Valley." It is from this word that we get "Nile."

AMAZON



Description: Flowing from Peru to Brazil and into the Atlantic Ocean, the Amazon is the world's highest-volume river.

Origin: The most commonly cited story says that in the 16th century, tribal warriors waiting on the banks attacked Spanish explorers sailing upriver. Because some of those warriors were women, the explorers believed they were Amazons, the female army from Greek mythology -hence the name. Another theory: It's a derivation of Amassona, meaning "boat destroyer." It was called that by indigenous people because of the Amazon's tidal bores, locally known as pororoca. These bores occur during the high spring tides, which create devastating waves that can travel several miles upriver.