This video explains a recent discovery of a campsite alongside a river in Coopers Ferry, Idaho that is 16,000 years old, being the oldest definitive evidence of humans in North America.  The site proves that native Americans were on the continent 2,000 years earlier than previously thought.  The discovery shows that they arrived while ice sheets still covered the North American continent, which means that they almost certainly arrived by boat, and they arrived prior to the previously known “Clovis” peoples.