The earliest, and best-known, of these “founders” are called the Clovis people, named after a site in New Mexico where, in the 1930s, large, bifacially flaked stone spear points were found in direct association with mammoth bones (in some instances actually embedded in the rib bones on the mammoths). Clovis hunters left their stone points and butchered animal bones at kill sites scattered across much of North America. When radiocarbon dating was introduced in the 1950s, Clovis sites were shown to range in age from about 11,000 to 11,400 years old – several thousands of years older than any other sites in the Americas (at least that was the thought then), just shortly after the corridor had opened up.
Everything seemed to fit quite nicely: no people in the Americas before 12,000 years ago (because of the ice sheets), the opening of an ice-free corridor beginning around 12,000 years ago, and the “sudden” appearance of Clovis at about 11,400 years ago, and their seemingly rapid spread over much of North America. Thus Clovis were the First Americans.