The United Nations Educational, Scientific and Cultural Organization (UNESCO) seeks to encourage the identification, protection and preservation of cultural and natural heritage around the world considered to be of outstanding value to humanity. This is embodied in an international treaty called the Convention Concerning the Protection of the World Cultural and Natural Heritage, adopted by UNESCO in 1972. The World Heritage List currently includes 830 properties forming part of the cultural and natural heritage which the World Heritage Committee considers as having outstanding universal value. These include 644 cultural, 162 natural and 24 mixed properties in 138 Countries. World Heritage designation of natural areas where geology is a primary resource has helped to raise the profile of geologic heritage preservation efforts in Europe, China, and North America.
In the United States, the NPS serves as chief steward of the nation's natural and cultural heritage. The Secretary of the Interior, through the National Park Service, is responsible for identifying and nominating U.S. sites to the World Heritage list. The Service's Office of International Affairs provides staff support for U.S. participation in the World Heritage Convention.
There are currently twenty (20) World Heritage sites in the United States (including two sites jointly administered with Canada). The U.S. Department of the Interior, in cooperation with the Federal Interagency Panel for World Heritage has identified many more sites (cultural and natural) as likely to meet the criteria for future nomination to the World Heritage List.