November 2016 - Archaeologists call the time just after people first came to North America the Paleo-Indian period. During the Paleo-Indian period, all the people in North America were nomads and got their food by hunting and gathering, and especially by fishing. Some of these people stayed in Alaska.
Other people gradually went south along the Pacific coast, looking for warmer weather, little by little. Most of them probably got most of their food by fishing, gathering shellfish, and hunting seals. Slowly, some people reached Central America and then South America.
Gradually, as the weather grew warmer, other people started to explore the lakes and rivers further east, spreading out across America. They ate fish from the lakes and rivers. They hunted the mammoth as they went, so many that they killed all of them, and most of the other big mammals. As the mammoth became extinct, the Paleo-Indians began to hunt buffalo instead. They used spears and atlatls to hunt. Eventually they reached the east coast of North America. By 12,500 BC, there were people living in Florida. Here there were still mammoths, but they didn't last long. All up and down the East Coast, like other Stone Age people, the Native Americans ate a lot of fish and shellfish.
By the time Native Americans had covered the whole country, people in North America had developed different languages, and couldn't understand each other talking anymore.
The cold snap we call the "Younger Dryas," which started about 11,000 BC and ended about 9,500 BC when warmer weather came back, created a good environment for Native Americans to live in, with plenty of variety.