From the source in British Columbia to the mouth in Alaska the Yukon River is 1,984 miles in length. The Mackenzie River in the Northwest Territories is the longest in North America at 2,635 miles...
There are over 1,100 tributaries that flow into the Amazon River. The three longest are the Madeira River(1), Purus River(2) and the Japur River(3).Madeira River