Pre-Columbian America

Asian nomads are thought to have entered the Americas via the Bering Land Bridge (Beringia), now the Bering Strait and possibly along the Northwest coast. Genetic evidence found in Amerindians' maternally inherited mitochondrial DNA (mtDNA) supports the theory of multiple genetic founding populations migrating from Asia, although it does not rule out a single migration. Over the course of millennia, people spread throughout North America and South America. Exactly when the first group of people migrated into the Americas is the subject of much debate. One of the earliest identifiable cultures was the Clovis culture, with sites dating from some 13,000 years ago. However, older sites dating back to 20,000 years ago have been claimed. Some genetic studies estimate the colonization of the Americas dates from between 40,000 to 13,000 years ago. Also, multiple waves of immigration have been suggested. Early Paleoamericans soon spread throughout the Americas, diversifying into many hundreds of culturally distinct nations and tribes.  Paleoindian adaptation across North America was likely characterized by small, highly mobile bands consisting of approximately 20 to 50 members of an extended family.

The Mississippian culture  ( 800 CE  to 1500 CE ) was spread across the Southeast and Midwest from the Atlantic coast to the edge of the plains, from the Gulf of Mexico to the Upper Midwest, although most intensively in the area along the Mississippi River. One of the distinguishing features of this culture was the construction of large earthen mounds, continuing the moundbuilding traditions of earlier cultures. They grew maize  and other crops intensively, participated in an extensive trade network, and had a complex stratified society. The Mississippians first appeared around 1000 CE, following and developing out of the less agriculturally intensive and less centralized Woodland period. The largest site of this people, Cahokia — located near modern East St. Louis, Illinois — may have reached a population of over 20,000.

A Short History of the United States audiobook

Channing's best known work, A History of the United States, is regarded as one of the most complete and accurate accounts of American history and received the 1926 Pulitzer Prize for History. 

European Exploration  and Settlement