The earliest people in the Americas probably were Asians who crossed the prehistoric land bridge across the Bering Strait. They were largely of Mongoloid ancestry.
The earliest inhabitants of Arizona, some archeologists believe, were prehistoric peoples who roamed the American southwest about 20,000 years ago.
The Transcontinental Railroad was a miracle of its time. Learn about the history of the Transcontinental Railroad and how the Transcontinental Railroad changed the country.