54 U.S.C. § 100102

In this title: (1) Director .— The term “Director” means the Director of the National Park Service. (2) National park system .— The term “National Park System” means the areas of land and water described in section 100501 of this title . (3) Secretary .— The term “Secretary” means the Secretary of the Interior. (4) Service .— The term “Service” means the National Park Service. (5) System .— The term “System” means the National Park System. (6) System unit .— The term “System unit” means one of the areas described in section 100501 of this title .