The Hopewell tradition (also called the Hopewell culture) describes the common aspects of the Native American culture that flourished along rivers in the northeastern and midwestern United States from 200 BC to 500 AD, in the Middle Woodland period. The Hopewell tradition was not a single culture or society, but a widely dispersed set of related populations. They were connected by a common network of trade routes, known as the Hopewell Exchange System.