Department of the Interior

United States Department of the Interior was a pre-War department of the United States government. The Department of the Interior was a federal executive department responsible for the conservation of most federal lands, natural resources, and other related entities, such as the National Park Service and United States Geological Survey.

Background
The National Park Service, a division of the Interior Department responsible for the maintenance and protection of a majority of the public federal lands, is mentioned numerous times across the Fallout series, most notably through Acadia, Grand Canyon, Kanawha, and Zion National Park.

The department worked closely with the Vault-Tec Corporation, at least in Appalachia, providing geological data for the company to construct their vaults.

During the Great War, the Secretary of the Interior took refuge in the Whitespring bunker alongside the Secretary of the Treasury and Secretary of Agriculture Thomas Eckhart, though died shortly after arrival.

Outside of the control of the DOI, the federal government would see fit to revoke the national park status of the Grand Canyon, effectively taking responsibility for the Grand Canyon from the Interior and into the hands of corporations to exploit its natural resources.