Poverty Point sites in Louisiana and western Mississippi exhibit the first major residential settlements and monumental earthworks in the United States. Although the Poverty Point culture is not well understood in terms of social organization, it was involved in the transportation of nonlocal raw materials (for example, shell, stone, and copper) from throughout the eastern United States into the lower Mississippi River Valley to selected sites where the materials were worked into finished products and …showed first 75 words of 1325 total…

…showed last 75 words of 1325 total…A.D. 400 might have affected yields of gathered foods, such as nuts or starchy seeds, thereby disrupting the trade networks. A fourth and possibly interrelated reason is that intensified horticulture became so successful that increased agricultural production may have reduced variation in food resource availability between differing areas. This reliance on horticulture, involving only a few types of plants, would have carried with it a risk where variations in rainfall or climate could cause famine