Over time, indigenous cultures in North America grew increasingly complex, and some, such as the pre-Columbian Mississippian culture in the southeast, developed advanced agriculture, architecture, and complex societies. The city-state of Cahokia is the largest, most complex pre-Columbian archaeological site in the modern-day United States. In the Four Corners region, Ancestral Puebloan culture developed from centuries of agricultural experimentation. The Haudenosaunee, located in the southern Great Lakes region, was established at some point between the twelfth and fifteenth centuries. Most prominent along the Atlantic coast were the Algonquian tribes, who practiced hunting and trapping, along with limited cultivation.
Estimating the native population of North America at the time of European contact is difficult.Douglas H. Ubelaker of the Smithsonian Institution estimated that there was a population of 92,916 in the south Atlantic states and a population of 473,616 in the Gulf states, but most academics regard this figure as too low. AnthropologistHenry F. Dobyns believed the populations were much higher, suggesting around 1.1 million along the shores of the Gulf of Mexico, 2.2 million people living between Florida and Massachusetts, 5.2 million in the Mississippi Valley and tributaries, and around 700,000 people in the Florida peninsula.
In the early days of colonization, many European settlers were subject to food shortages, disease, and attacks from Native Americans. Native Americans were also often at war with neighboring tribes and European settlers. In many cases, however, the natives and settlers came to depend on one another. Settlers traded for food and animal pelts; natives for guns, tools and other European goods. Natives taught many settlers to cultivate corn, beans, and other foodstuffs. European missionaries and others felt it was important to “civilize” the Native Americans and urged them to adopt European agricultural practices and lifestyles. However, with the increased European colonization of North America, the Native Americans were displaced and often killed. The native population of America declined after European arrival for various reasons, primarily diseases such as smallpox and measles.
European settlers also began trafficking of African slaves into Colonial America via the transatlantic slave trade. Because of a lower prevalence of tropical diseases and better treatment, slaves had a much higher life expectancy in North America than in South America, leading to a rapid increase in their numbers. Colonial society was largely divided over the religious and moral implications of slavery, and several colonies passed acts both against and in favor of the practice. However, by the turn of the 18th century, African slaves had supplanted European indentured servants as cash crop labor, especially in the American South.