Aboriginal people are believed to have traveled to North America by?

There are a number of theories about how the first humans arrived in North America. The first thing to understand is that we do not know for sure how the native people arrived or when they arrived—as archaeology becomes more advanced, we are finding evidence of people in North America from longer and longer ago. Now it is thought that there have been people living there for 20,000 years. Many Native American tribes, including the Navajos, disbelieve the theory that their ancestors came from elsewhere at all. Their stories say that their people once lived underground and came up to the surface. Some people think that native peoples sailed across the Atlantic to North America from Europe, based on archaeological evidence showing similarities between early weapons.
However, the most traditional theory is that Native Americans walked to North America across the Bering Land Bridge from Asia.
Look at the link below for some fascinating debate on this subject.
http://www.bbc.com/earth/story/20170328-the-first-people-who-populated-the-americas