Mississippi – Missouri – Jefferson, North America (6,275 km)

Top 4 in Top 10 Longest rivers of the planet.

The Mississippi River is a river in North America. The river is 3,733 kilometres (2,320 mi) from Lake Itasca to the Gulf of Mexico. Another river in North America is the Missouri River, with a length of 3,767 kilometres (2,341 mi) from the junction of the Jefferson River, the Madison River and the Gallatin River to the Mississippi River. The subsequent rivers Jefferson, Missouri and Mississippi formed the largest river system in North America.