A century ago, archeologists believed human beings had occupied the Americas for just 3,000 years. Then, a series of discoveries on the plains of West Texas and eastern New Mexico transformed that view.

In 1932, archeologists excavated the remains of a mammoth in Blackwater Draw, near Portales, New Mexico. Among the bones, they found a spearpoint. It was proof that humans had lived in North America as far as back as the Ice Age – and had shared the continent with a stunning array of now-vanished mammals.

At Blackwater Draw National Landmark, and Blackwater Draw Museum at Eastern New Mexico University, visitors glimpse the Paleolithic past.

In 1875, Quanah Parker and his Comanches ...