In 1946, a group of scientists formed the Ecologist Union in order to preserve endangered ecological areas. Four years later, the organization changed its name to the Nature Conversancy and on October 22, 1951, the group was incorporated as a nonprofit organization in the District of Columbia. In 1955, the organization purchased 60 acres of land in the state of New York, its first conservation holdings.

The Conservancy is now an international nonprofit organization with agencies in all 50 states and in 27 countries and protects over 117 million acres of land and 5,000 miles of river around the world. In the Dakotas, the Conservancy protects nearly 100,000 acres of land in twelve different locations, the largest being the Cheyenne River Canyons located in the Black Hills of South Dakota. The largest land area in North Dakota is the Davis Ranch where the Conservancy is using grazing patterns of the bison for domestic cattle.

The Nature Conservancy is one of the top 15 charitable institutions in the nation with over one million members and supporters. Its mission is to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive. The organization determines areas that need protection by using a scientific based approach called Conservation by Design. This approach uses strategies to improve priority conservation sites by addressing five initiatives: marine and freshwater conservation, global warming, fire, and invasive species.