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). The system encompasses 84.6 million acres of land--80.6 million acres federally owned and 4.0 million acres of private and other public land (e.g., state land) within NPS unit boundaries. Units range in size from less than one acre to millions of acres. Nearly two-thirds of the total acreage is in Alaska. In 1872, Congress designated Yellowstone as the world's first national park. Subsequently, the nation slowly developed a system of national parks. While some new areas were administered by DOI, others were managed by different agencies. A 1916 law created the NPS within DOI to protect existing and future parks, monuments, and other areas. It charged NPS with promoting and regulating the use of those areas both to conserve them and to provide for their enjoyment by the public. A 1933 executive order furthered the development of a national system by transferring dozens of sites to NPS from other agencies. The General Authorities Act of 1970 made explicit that all areas managed by NPS were part of a single system, and gave all units of the system equal standing with regard to resource protection. Statutes authorizing particular units sometimes provide additional management direction for those units. Units of the National Park System generally are managed to preserve resources in their natural or historical conditions for the benefit of future generations. Thus, hunting, mining, and other consumptive resource uses generally are not allowed. However, in the laws creating units, Congress sometimes has specified that some of those uses are allowed. Today, there are more than 20 different designations (i.e., titles) for units of the National Park System, reflecting the diversity of the areas. There is no statute that sets out and defines all the designations, and Congress has discretion in choosing the type of designation for a unit being established. While some designations are descriptive and possibly self-explanatory, such as "battlefield," others have been used in different ways. For instance, the designation "national monument" has been given to a variety of areas, including natural reservations, historic military forts, prehistoric ruins, fossil sites, and the Statue of Liberty. Some classifications (such as "national park") are unique to NPS, while others (such as "national recreation area") also are used by other land management agencies. Of the 412 units within the National Park System, 59 are national parks, the so-called crown jewels of the park system. Other commonly used titles include national historic sites (78), national monuments (83), national historical parks (50), national memorials (30), national recreation areas (18), and national preserves (19). National Park System units are created by acts of Congress, except that national monuments also may be added by presidential proclamation. The Antiquities Act of 1906 (54 U.S.C. SS320301 et seq.) authorizes the President to create national monuments on land that is already federally owned or controlled, and that contains historic landmarks, historic and prehistoric structures, or other objects of historic or scientific interest. Presidents have designated 150 monuments since 1906. Congress has subsequently converted many of them, such as the Grand Canyon, to national parks. Most monuments are managed by NPS, with many newer monuments managed by the Bureau of Land Management or other agencies. 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. Bills to create units generally are within the jurisdiction of the House Committee on Natural Resources and the Senate Committee on Energy and Natural Resources, with appropriations typically contained in Interior, Environment, and Related Agencies' appropriations acts. Congress sometimes has enacted free-standing legislation to add units to the National Park System. Congress also has authorized units as part of omnibus public land laws containing dozens of measures related to lands and recreation. Legislation creating a new unit is often preceded by legislation to authorize an NPS study of the area, as described below. Provisions of law govern Congress's consideration of measures to create units of the National Park System. In 1998, Congress amended existing law pertaining to creating units ( P.L. 105-391 ) to standardize procedures, improve the information about potential additions, prioritize areas, focus on outstanding areas, and ensure congressional support for area studies. Current law does not appear to explicitly require an NPS area study before Congress adds a unit to the National Park System, but any such study requires "specific authorization of an Act of Congress" (54 U.S.C. SS100507). Before 1998, studies were prepared at the initiative of NPS, individual Members of Congress, and other entities, as well as required by authorization and appropriations laws. The 1998 statutory change sought to eliminate these separate sources for initiating studies, on the grounds that in some years funding was insufficient to cover all studies, and ongoing studies sometimes were not completed because funds were earmarked for other studies. However, NPS has standing authority to take certain actions, provided that they cost less than $25,000. These actions include preliminary activities, such as resource assessments of areas, "reconnaissance surveys" of areas, and updates of previous studies. After funds are available, NPS must complete a study of an area within three fiscal years. In practice, studies have taken longer to prepare. This is due to the large number of studies authorized by Congress and the extent of available resources. The length of time for completing studies generally ranges from three to six years, depending on the complexity, such as the number of stakeholders and whether any environmental issues may be involved. The cost of preparing a study also depends on its complexity, with the average cost estimated at roughly $500,000. Studies must include public involvement, with at least one public meeting held in the local area, and reasonable efforts to notify affected state and local governments and landowners. Studies also must comply with the National Environmental Policy Act of 1969 (NEPA), which requires an assessment of the potential impact of the proposed action on the human environment. The NPS studies must consider certain factors established in P.L. 105-391 to promote the consistency and professionalism of the studies. 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. An area will be regarded as nationally significant if it is an outstanding example of a resource; exceptionally illustrates or interprets natural or cultural themes of our country's heritage; provides extraordinary opportunities for public enjoyment or scientific study; and contains a true, accurate, and relatively unspoiled resource. In evaluating national significance, the NPS considers natural and cultural areas, with cultural areas evaluated under the process for national historic landmarks (36 C.F.R. Part 65). Examples of nationally significant natural areas might include a refuge that is critical for the survival of a species, a rare landform, or an outstanding scenic area. Cultural areas might include districts, sites, structures, or objects of exceptional quality in interpreting our nation's heritage, such as those with distinctive architectural types. Cultural entities generally exclude cemeteries, birth places, graves, religious properties, relocated structures, reconstructed buildings, and properties of significance within the past 50 years. In the past, NPS also evaluated the national significance of recreational areas, but now recreational values are assessed in evaluating natural and cultural areas. NPS views an area as suitable if it portrays a natural or cultural resource insufficiently included in the system, unless a similar area is managed for public use by another agency. An area is feasible to add if it is large enough, configured so as to allow long-term protection and public use, and affordable to manage. Other important issues in assessing the feasibility of adding an area to the National Park System include ownership of the land and the cost of acquiring it, access, current and potential land uses, threats to resources, public support, and staff or development requirements. For instance, privately owned land that the owner is unwilling to sell, or that would be expensive to acquire, might not be viewed as feasible. NPS studies of potential new areas must also evaluate a variety of other factors, such as the rarity and integrity of the resources, the socioeconomic effects of addition, and the interpretive and educational uses of the site, among others. Studies also usually discuss boundary possibilities. NPS statistics show that since 2000, about one in three to one in four area studies has concluded that an area is eligible for inclusion. In studying an area, NPS must consider whether protection by means other than NPS management is appropriate. Options include administration by other federal agencies, state or local governments, Native American authorities, and the private sector. Consideration may be given to technical or financial assistance; other designations, including wilderness, national trail, or national historic landmark; and cooperative management between NPS and another agency. NPS generally will not recommend adding an area to the National Park System if another arrangement already provides, or could provide for, sufficient protection and public use. The study must identify the best alternative(s) for protecting resources and allowing public enjoyment. Each study sent to Congress must be accompanied by a letter from the Secretary that identifies the preferred management option for the area, to minimize uncertainty about NPS's position. P.L. 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. NPS must consider three issues in developing for Congress the list of areas recommended for study: (1) whether an area is nationally significant and would be a suitable and feasible addition to the National Park System; (2) whether an area represents or includes themes, sites, or resources "not already adequately" represented in the National Park System; and (3) requests for studies in the form of public petitions and congressional resolutions (the "popular demand" factor). 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. These previously studied areas are to be ranked in order of priority for addition to the park system and supported by current data. In the past, NPS has ranked areas that passed the initial screening and recommended the highest-priority areas to Congress for study. However, the George W. Bush Administration did not submit the annual lists, partially because that Administration generally did not support expanding the National Park System. Like the Bush Administration, the Obama Administration has in most years not submitted lists of areas for potential study or addition to the park system. The Obama Administration submitted the lists once, in August 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, new information, and reinterpretations. A related issue is how to properly maintain existing and new units given limited fiscal and staffing resources. As noted, the George W. Bush Administration generally did not support the creation of new park units and the expansion of existing units, as it sought instead to focus funds on maintaining current units. The Bush Administration supported some expansions on the grounds that they could be accomplished for relatively little cost. Supporters of new units have charged that the older units are the most costly. Initially, the Obama Administration also expressed a need to focus attention and resources on the current system, including the maintenance backlog, "rather than continuing the rapid expansion of new NPS responsibilities." Subsequently, in a number of instances the Administration has testified in favor of creating new units of the National Park System, studying additional areas, and expanding existing units. 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. Critics contend that the system has been weakened by including inappropriate areas, especially where authoritative information was unavailable, incomplete, or disregarded in favor of political considerations. Others counter that there will always be disagreement over the worth of areas, and that recently added areas have been held to the same high standards as older units. Another issue has been whether particular resources are better protected outside the National Park System, and how to secure the best alternative protection. It is generally regarded as difficult to meet the criteria and to secure congressional support and funding for expanding the National Park System. While there is often considerable interest in establishing new units, usually no more than a handful of units are created each Congress. Many areas are preserved outside the National Park System. Some of these are protected with recognition or assistance by the NPS. 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. Affiliated areas are nationally significant but do not meet the other criteria for inclusion in the Park System. Under NPS policy, they are worthy of special NPS recognition or assistance beyond existing programs, are managed in accordance with standards applicable to park units, and are to receive sustained resource protection as detailed in an agreement between the NPS and the nonfederal manager of the area. In the past, the affiliated areas have included properties primarily recognized for cultural or commemorative worth. Affiliated areas have been created by act of Congress and by designation of the Secretary of the Interior. Currently, there are about two dozen affiliated areas. Congress has established national heritage areas containing land and properties that reflect the history of their people. Typically, heritage areas consist mainly of private properties and may include natural, scenic, historic, cultural, or recreation resources. Conservation, interpretation, and other activities are handled by partnerships among federal, state, and local governments and nonprofit organizations, and for each area Congress has recognized a "management entity" to coordinate efforts. The NPS supports these efforts through technical and financial assistance, and such support is not intended to be permanent. Supporters of heritage areas have asserted that they reduce pressure to add new, costly, and possibly inappropriate areas to the National Park System, while opponents have feared that they could be used to extend federal control over non-federal land. Differences also have existed over whether to create a comprehensive heritage program containing priorities and standards for establishing heritage areas. Some programs give places honorary recognition. Cultural resources may be listed by the NPS in the National Register of Historic Places, as meriting preservation and special consideration in planning for federal or federally assisted projects. The Secretary of the Interior may designate natural areas as national natural landmarks, and cultural areas as national historic landmarks. National parks, monuments, and other areas of international worth may, at the request of the United States, be recognized by the United Nations as world heritage sites or biosphere reserves. Congress or the Secretary of the Interior may designate rivers as components of the National Wild and Scenic Rivers System, and trails as part of the National Trails System. The NPS also supports local and state governments in protecting resources. The agency may provide grants for projects (including acquisition and development of recreational facilities) and technical assistance (for conserving rivers, trails, natural areas, and cultural resources). In addition to this range of NPS programs, resources are protected by the private sector, state and local governments, and other federal agencies.

Summary:
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.