This reference volume serves as the definitive administrative index for the United States National Park System as of 1989. The publication provides a comprehensive catalog of all units managed by the National Park Service, including national parks, monuments, historic sites, and related areas. It functions as an official record of federal land designations, boundary definitions, and administrative classifications for public and governmental use.

Researchers and historians utilize this text as a foundational archival document for tracking the evolution of federal land management. It is recognized as a standard reference tool for verifying the status and nomenclature of protected areas during the late twentieth century.