How Long is the Amazon River?

According to U.S. Geological Survey, the Amazon River is the second longest river in the world with length of  4,000 miles (6,437 kilometers).

Longest Rivers in the world are:

Nile River - 4,132 miles (6,650 kilometers).
Amazon River - 4,000 miles (6,437 kilometers)
Yangtze River  - 3,915 miles (6,301 kilometers)

The longest U.S. river is the Missouri with 2,540 miles (4,088 kilometers)