Archaeologists have studied this portion of the Missouri River Valley since 1895, excavating, mapping, recording, and preserving prehistoric sites along the river. By the 1930s, aerial photography had become an important tool for finding large village sites, and in the 1950s the region gained national recognition as Smithsonian scientists and university field crews worked in the area. Rising water behind the Missouri's dams deluged many sites and created salvage archaeology, with crews working quickly to excavate what they could. State and federal laws governing how archaeological work may be conducted have evolved over the years, and new scientific methods have also changed such research. The Missouri River Valley continues to reveal much about the area's rich heritage, including evidence from animal bone artifacts that shows the types of food eaten centuries ago and how bones were used to make tools and decorations, as well as distinctive pottery styles that help track the movements of tribes over time.