	Overview of the System

The National Park System contains 412 units throughout the nation. They are administered by the National Park Service (NPS) in the Department of the Interior (DOI). Today, there are more than 20 different designations (i.e., titles) for units of the National Park System, reflecting the diversity of the areas. An act of Congress creating a National Park System unit may explain the unit's purpose; set its boundaries; provide specific directions for land acquisition, planning, uses, and operations; and authorize appropriations for acquisition and development. Criteria for Studies

The NPS studies must consider certain factors established in P.L. The law directs NPS to assess whether an area contains natural or cultural resources that are nationally significant, whether it constitutes one of the most important examples of a type of resource, and whether it is a suitable and feasible addition to the system. The NPS has developed criteria for determining national significance, suitability, and feasibility. 105-391 also requires the Secretary of the Interior to recommend annually to Congress a list of areas for study for potential inclusion in the National Park System. The NPS also must submit to Congress a list of areas previously studied that contain primarily historical resources and a list of areas with natural resources. Issues

The addition of units to the National Park System sometimes has been controversial. Some discourage adding units, asserting that the system is "mature" or "complete," while others assert that the system should evolve and grow to reflect current events, new information, and reinterpretations. A related issue is how to properly maintain existing and new units given limited fiscal and staffing resources. Differences exist as to the relative importance of including areas reflecting U.S. natural, cultural, and social history. The adequacy of standards and procedures for assuring that the most outstanding areas are included in the system also has been debated. Another issue has been whether particular resources are better protected outside the National Park System, and how to secure the best alternative protection. Alternatives to Inclusion in the National Park System

It is generally regarded as difficult to meet the criteria and to secure congressional support and funding for expanding the National Park System. Certain areas that receive technical or financial aid from the NPS, but are neither federally owned nor directly administered by the NPS, have been classified by the NPS as affiliated areas. Some programs give places honorary recognition. The NPS also supports local and state governments in protecting resources.
The National Park System includes 412 diverse units administered by the National Park Service (NPS) in the Department of the Interior. Units generally are added to the National Park System by acts of Congress, although the President may proclaim national monuments for inclusion in the system on land that is federally managed. An act of Congress creating a National Park System unit may explain the unit's purpose; set its boundaries; provide specific directions for land acquisition, planning, uses, and operations; and authorize appropriations for acquisition and development. Today, there are more than 20 different designations (i.e., titles) for units of the National Park System, reflecting the diversity of the areas.
Before enacting a law to add a unit, Congress often first enacts a law requiring the NPS to study an area, typically to assess its national significance, suitability and feasibility, and management options. When Congress directs the NPS to prepare a study, the agency must assess whether an area contains natural or cultural resources that are nationally significant, constitutes one of the most important examples of a type of resource, and is a suitable and feasible addition to the park system. The agency also is to consider certain other factors established in law (e.g., threats to resources).
The Secretary of the Interior is required by law to recommend annually to Congress a list of areas for study for potential inclusion in the National Park System. The Secretary is also required to submit to Congress a list of areas previously studied that contain primarily historical resources and a list of areas with natural resources. Since 2000, the Secretary has submitted such recommendations once, in 2012.
The addition of units to the National Park System sometimes has been controversial. Some discourage adding units, asserting that the system is "mature" or "complete," while others assert that the system should evolve and grow to reflect current events, reinterpretations, and a changing U.S. population. A related issue is how to properly maintain existing and new units given limited fiscal and staffing resources. Differences exist on the relative importance of including areas reflecting our natural, cultural, and social history. The adequacy of standards and procedures for ensuring that the most outstanding areas are included in the Park System also has been debated.
It is generally regarded as difficult to meet the criteria and to secure congressional support and funding for expanding the National Park System. Thus, another issue has been whether particular resources are better protected outside the National Park System, and how to secure the best alternative protection. Certain areas that receive technical or financial aid from the NPS, but are neither federally owned nor directly administered by the NPS, include affiliated areas and national heritage areas. Some programs give places honorary recognition. The NPS also supports local and state governments in protecting resources through grants for projects and technical assistance.