Economy

This Is the Longest River in America

(Updated) The world’s two longest rivers, the Amazon and the Nile, each stretch over 4,000 miles. Nothing in the United States comes close to that length. America’s longest river, according to the U.S. Geological Survey, is the Missouri River. At 2,450 miles long, it is just ahead of the Mississippi, which spans 2,340 miles.

The Missouri River starts in the Rocky Mountains in Montana, about 4,000 feet above sea level. It ends where it joins the Mississippi River in St. Louis. On its way, it runs through parts of Montana, North Dakota, South Dakota, Nebraska and Missouri.

Among its primary uses are the generation of hydroelectric power and irrigation. There are 15 dams along its route. In terms of its effect on agriculture in the United States, according to American Rivers:

About one-fourth of all the agricultural land in the U.S. is found in the Missouri River watershed, which provides more than one-third of the country’s wheat, flax, barley, and oats. Its significance to American culture past and future cannot be overstated.


Like most large rivers, the Missouri has caused devastating floods. The largest, according to the Missouri Secretary of State, happened in June and July of 1844. The river crested 41 feet in St. Louis. The agency’s analysis also says that the 1993 flood of the Missouri and Mississippi Rivers triggered the greatest economic catastrophe in Missouri history.

America’s largest rivers have been threatened by pollution for years. The St. Louis Post-Dispatch quoted a U.S. Environmental Protection Agency report: “The Missouri River ranked seventh with nearly 5 million pounds of dumped toxins.” The Ohio River had the largest toxic discharge at 32 million pounds.

These U.S. rivers are more than 1,000 miles long:

  • Missouri: 2,540 miles
  • Mississippi: 2,340 miles
  • Yukon: 1,980 miles
  • Rio Grande: 1,900 miles
  • St. Lawrence: 1,900 miles
  • Arkansas: 1,460 miles
  • Colorado: 1,450 miles
  • Atchafalaya: 1,420 miles
  • Ohio: 1,310 miles
  • Red: 1,290 miles
  • Brazos: 1,280 miles
  • Columbia: 1,240 miles
  • Snake: 1,040 miles

Click here to read about the worst floods in American history.