Mississippian culture grew in the southern Mississippi River Valley. The Mississippian American Indians were farmers and mound builders, and the culture spread along rivers through modern-day central and eastern North America. Some aspects of Mississippian life grew out of earlier regional cultures, but the Mississippians were also largely influenced by contact with Mayan and Zapotec traders.
Meriwether Lewis and William Clark explored the territories gained through the Louisiana Purchase. The Corps of Discovery set out from St. Louis and explored 8,000 miles along the Missouri and Columbia Rivers and reached the Pacific. The expedition returned in 1806.