First, we must acknowledge that this question presupposes that the three-wave theory of migration to the Americas is correct. This is a theory that remains very controversial.
According to the three-wave theory of migration to the Americas, there was a second wave of migration that arrived in the Americas about 12,000 years ago. This group is called the Na-Dene. It may be that it was this group that brought the Clovis culture that was once thought to be the first Native American culture. The descendants of the Na-Dene are thought to live today in the Southwestern United States, in Alaska and Northwestern Canada, and in some places along the West Coast of the continental US.