Department of Interior Challenge Coin. This is a great looking United States Department of the Interior (DOI) challenge coin. Coin has reeded edges and is about 1 9/16" in diameter. All details are raised lettering and gold plated. Coin is contained in an acrylic snap tight holder. The United States Department of the Interior (DOI) is the United States federal executive Department of the U S government responsible for the management and conservation of most federal land and natural resources, and the administration of programs relating to Native American, Alaskan Natives, Native Hawaiians, territorial affairs, and insular areas of the United States. About 75% of federal public land is managed by the department, with most of the remainder managed by the United States Department of Agriculture's United states Forest Service. The Department is administered by the United States Secretary of the Interior, who is a member of the Cabinet of the President. Despite its name, the Department of the Interior has a different role from that of the interior ministries of other nations, which are usually responsible for police matters and internal security. In the United States, national security and immigration functions are performed by the Department of Homeland Security primarily and the Department of Justice secondarily. The Department of the Interior has often been humorously called "The Department of Everything Else" because of its broad range of responsibilities.