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Cover to America's National Park Service: The Critical Documents
Cover Page


Table of Contents


The Early Years,

Defining The System,

The New Deal Years,

The Poverty Years,

Questions of
Resource Management

The Ecological Revolution,

Transformation and

A System Threatened,

Summaries of
Lengthy Documents

About the Editor

America's National Park System:
The Critical Documents
Chapter 6:
The Ecological Revolution: 1964 - 1969
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The preservation of historic structures, objects and sites (grounds or terrain) is fundamental to their continued use and benefit. Hence, preservation is a prerequisite to use. In actual practice, the two objectives usually complement rather than conflict with each other. Occasionally, however, use, such as at a historic building, must be regulated and, indeed, limited in order to preserve the resource.

Management of historical areas also encourages appropriate uses of such natural and recreational resources as may be within a historical area when such uses can be accommodated without detriment to the preservation and use of the historical resources.

Much of the success in preserving and interpreting the historic resources within an area depends upon the quality of the environment surrounding the area. Management, therefore, is desirous of cooperating with adjoining owners and agencies responsible for planning and managing properties within the vicinity of a historical area which may influence the environment of the area.

In its management of historic properties, the National Park Service uses the term historic in a broad sense to include prehistoric as well as historic periods, or a combination of the two. Likewise, for management purposes, historic resources are defined as follows:


A historic site is a distinguishable piece of ground or area upon which occurred some important historic event, or which is importantly associated with historic events or persons, or which was subjected to sustained activity of man—historic, prehistoric, or both. The topography itself may have been shaped by the activity of man. Examples of historic sites (grounds or terrain) are battlefields, historic campgrounds, historic trails, and historic farms.


A historic structure is a work of man, either prehistoric or historic, consciously created to serve some form of human activity. A historic structure is usually, by nature or design, immovable. Besides buildings of various kinds, the term includes engineered works such as dams, canals, bridges, stockades, forts and associated earthworks serving a similar purpose, Indian mounds, gardens, historic roads, mill races and ponds.


Historic objects are material things of functional, esthetic, cultural, or scientific value that are usually, by nature or design, movable. They are ordinarily regarded as museum specimens. If, however, they are large and not readily portable, they are ordinarily treated as structures (e.g., nautical vessels, statues).


Historic sites (grounds or terrain), structures, and objects are the prime resources within the historic areas of the National Park System. In addition, such historic resources may exist, in varying degree, in those units of the System classified as natural areas and recreational areas. Regardless of the location of such historic resources in the System, the administrative policies in this section apply to their preservation, management, and use.

All of these resources enrich and illuminate the cultural heritage of our Nation. Accordingly, it is appropriate and desirable that these historic resources be made available for public use to the greatest extent practicable. To achieve this objective, however, it is neither necessary nor practicable that each resource, especially structures, be accorded the same detailed research and expensive effort required for an exact full restoration.

As to a historic structure, it is often better to retain genuine old work of several periods, which may have cultural values in themselves, than to restore the whole to its aspect at a single period.

Moreover, some historic structures, occasionally, are included within the National Park System incidental to the establishment of an area for another purpose, e.g., nature preservation or commemoration of a significant event with which a building may not be directly associated. Often these structures are already in an advanced state of deterioration. Their preservation or restoration, in these circumstances, may not be warranted by their significance and the cost of preservation or restoration. In such cases, appropriate examples should be recorded by the Historic American Buildings Survey whenever possible. On the other hand, when sound structures of intrinsic artistic merit in themselves or that are valuable in illustrating the history of the Nation, a State, or locality are included in similar circumstances, their retention and use is encouraged. Appropriate examples may be restored to one of the degrees included below.

Consistent with the congressional policy enunciated in the Historic Sites Act of 1935 and the National Historic Preservation Act of 1966, the historic structures within the areas of the National Park System are classified according to the following definitions of significance:

First Order of Significance. Those structures which, in terms of uniqueness, antiquity, or historical, architectural, or cultural associations as assessed against the criteria of national significance applied in evaluating potential National Historic Landmarks, are significant in the preservation and interpretation of the history of the Nation.

Second Order of Significance. Those structures significant primarily in the presentation and interpretation of the history of a region or State.

Third Order of Significance. Those structures significant primarily in the presentation and interpretation of the history of a community or locality.


The historic structures within the areas of the National Park System are accorded a variety of treatments depending upon their significance. The types of treatment which may be accorded these historic structures are described as follows:

Preservation. Application of measures designed to sustain the form and extent of a structure essentially as existing when the National Park Service assumes responsibility. Preservation aims at halting further deterioration and providing structural safety but does not contemplate significant rebuilding. Preservation includes:

(a) Techniques of arresting or slowing the deterioration of a structure;

(b) Improvement of structural conditions to make a structure safe, habitable, or otherwise useful;

(c) Normal maintenance and minor repairs that do not change or adversely affect the fabric or historic appearance of a structure.

Restoration. The process of accurately recovering, by the removal of later work and the replacement of missing original work the inform and details of a structure or part of a structure, together with its setting, as it appeared at some period in time. Restoration includes:

(a) Full restoration—both exterior and interior

(b) Partial restoration—exterior, interior, or any partial combination. Partial restoration is adopted when only parts of a structure—external, internal, or in combination—are important in illustrating cultural values at its level of historic significance, or contribute to the values for which the area was designated.

(c) Adaptive restoration—all or a portion (facade, for example) of the exterior restored, with interior adapted to modern functional use. Adaptive restoration is the treatment for structures that are visually important in the historic scene but do not otherwise qualify for exhibition purposes. In such cases, the facade or so much of the exterior as is necessary, should be authentically restored to achieve the management purpose so that it will be properly understood from the public view. The interior, in these circumstances, is usually converted to a modern, functional use. The restored portion of the exterior should be faithfully preserved in its restored form and detail.

Reconstruction. The process of accurately reproducing by new construction the form and details of a vanished structure, or part of it, as it appeared at some period in time. Reconstruction includes:

(a) Full reconstruction.

(b) Partial reconstruction.


Consistent with the legislation involving a particular area and the primary purpose of the area, all historic structures in areas of the National Park System that may be worthy and practicable of preservation should be retained for public use. All such properties should be recorded on the List of Classified Structures. The List of Classified Structures should reflect the order of significance of the properties recorded, as determined by the appropriate Regional Director, with professional assistance from the Office of Archeology and Historic Preservation.


Preservation is the treatment to be considered first. And the important consideration is whether a historic site or structure should be retained in essentially the state in which it came under the control of the National Park Service.

Structures on the List of Classified Structures of either the first, second, or third orders of significance may be preserved on one of the following bases: (1) Preservation is the most desirable treatment;

(2) the significance and interpretive value of the structure does not justify the cost of restoration; (3) there are not sufficient data to permit accurate restoration; (4) restoration is indicated but must, for cost or other reasons, be postponed; (5) the structure upon acquisition already possesses the integrity and authenticity required; or (6) the work of a higher treatment has been completed, e.g., once restored, a structure is then preserved.


When needed to interpret properly the historic values of the area, historic structures may be fully and exactly restored when of the first order of significance or a vital element of a site or complex of structures of the first order of significance. Fully restored structures will usually be maintained for exhibition purposes only. Once restored, they should be faithfully preserved in form and detail.

When needed to interpret properly the historic values of the area, historic structures of the second and third orders of significance are eligible for lesser degrees of restoration, such as adaptive restoration or partial restoration. Moreover, such historic structures should serve living, utilitarian uses, consistent with interpretation of the historic values of the area.


Reconstruction should be authorized only when the following conditions are met:

(a) All or almost all traces of a structure have disappeared and its recreation is essential for public understanding and appreciation of the historical associations for which the park was established.

(b) Sufficient historical, archeological, and architectural data exist to permit an accurate reproduction.

(c) The structure can be erected on the original site or in a setting appropriate to the significance of the area, as in a pioneer community or living farm, where exact site of structures may not be identifiable through research.


In the preservation of historic structures, every attempt should be made to comply with local building and fire codes and to cooperate with local officials. However, compliance should not be allowed to destroy or impair the integrity of the structure. Where full compliance is not feasible, occupancy of the structure at any one time should be limited to the capacity of hall, stairways, and exits.

Where warranted by the significance or value of a historic structure or its contents, adequate fire warning and suppression systems should be installed. A detection system is preferable to a suppression system, which could do more damage than fire. Where a manned fire station exists near the structure, a detection system providing a signal directly to the local fire authorities should be installed. Also, fire personnel should be advised of any peculiarities or dangers inherent in the structure and the features and contents whose value warrants the greatest care in the event of fire.

Where a detection system of this type is not practicable, a suppression system should be installed. Fog or freon systems are preferable. Sprinkler systems should be used only in structures whose fabric and contents are not likely to be irreparably damaged by water. Foam systems should be used only when the structure can be swiftly vacated.

In planning and installing detection or suppression systems, the integrity of the structure and the requirements of its interpretation will be respected.


The purchase or acceptance as gifts of historic structures situated outside historical areas is permitted only when there is available an authentic structure that would otherwise have to be reconstructed for interpretive purposes in the area.

A historic structure that is germane to the interpretive theme of an area and that was formerly located on a site that has been included in an area of the System may be acquired and returned to that site.


Historic structures of the first order of significance bear an important relation to their sites and, therefore, should be preserved in situ. If, however, such a structure has been previously moved, it may be returned to its original location if desirable for interpretive purposes.

Historic structures of the second and third orders of significance may be moved when there is no feasible alternative for their preservation, when their importance is other than in direct relation to their location, or when desirable for interpretive purposes.

In moving a historic structure, every effort should be made to reestablish its historic orientation, immediate setting and general relationship to its environment. If it is necessary to move a number of buildings, they may be arranged in an ensemble appropriate to their historic character.


Modern additions, such as heating and air-conditioning equipment, are permitted in historic structures of the first order of significance to the extent that they can be concealed within the structure or its setting.

Other modern construction may be added to historic structures of the second or third orders of significance when necessary for their continued use. A modern addition should be readily distinguishable from the older work; however, the new work should be harmonious with the old in scale, proportion, materials, and color. Such additions should be as inconspicuous as possible from the public view and should not intrude upon the important historic scene.


Historic structures that are damaged or destroyed by fire, storm, earthquake, war, or other accident may be restored or reconstructed in accordance with the restoration and reconstruction policies stated herein.


By definition, ruins are classified as historic structures and will be accorded treatment as indicated herein for the several classes of historic structures.

The preservation techniques designed to arrest further deterioration of ruins are encompassed by the term "ruins stabilization."

Ruins on unexcavated sites should be stabilized only to the extent necessary to preserve them for further investigation. Sites should not be excavated until adequate provisions have been made for the stabilization of ruins as they are exposed. In cases where ruins are too fragile for direct contact, or where deterioration would result from contact, visitor use should be strictly limited or prohibited. The deliberate creation of ruins out of whole structures that come under the care of the National Park Service is prohibited.


Historic gardens, by definition, are classified as historic structures and will be accorded treatment as indicated for the several classes of historic structures. When restored, gardens should be provided intensive maintenance to preserve their correct historic character and prevent overgrowth.


Historic objects related directly to the history of the area may be acquired by gift, loan, exchange, or purchase, in conformance with legal authorizations and existing procedures and preserved in the area for study and interpretive purposes. A reasonable number of specimens not related directly to the history of the area, also, may be included in the collection for purposes of comparative study. The original fabric of historic structures should not be mutilated to secure specimens for museum collections. Where some of the original fabric is removed incidental to structural repair, such portions of the building may be kept in museum collections if they reveal significant facts about the structure. All historic objects for which the Service is responsible should be properly documented and recorded in accordance with prescribed procedures, and receive the curatorial care needed for optimum preservation.

Historic objects that are excess to the management needs of the Service may be disposed of in accordance with applicable laws and procedures.


The Federal Antiquities Act of 1906 (34 Stat. 225; 16 U.S.C. 431) makes it a Federal offense for any person to appropriate, excavate, injure, or destroy any historic or prehistoric ruin or monument, or any object of antiquity, situated on lands owned or controlled by the United States. The act, however, does authorize the Secretary of the Interior to issue permits for examination and excavation of ruins to properly qualified institutions subject to prescribed rules and regulations. The collecting of antiquities in historical areas is, therefore, not permitted, except by institutions under permit from the Secretary or by Service employees in the performance of their duties.


In the preservation and use of historic sites (grounds or terrain), manmade features introduced after the date or period of the event commemorated that are compatible with the historic scene may be retained, except where they hamper visitor understanding of the event commemorated or are incongruous intrusions on the historic scene. Natural accretions of time, such as forest growth, also may be retained unless it hampers visitor understanding of the event commemorated. To the extent necessary for visitor understanding, elements of the historic scene may be restored, including restoration of manmade features, vegetative growth, and historic land uses.


Agricultural uses, including demonstration farms, are encouraged in historical areas where they conform to those in practice in the historical period of the area.

Agricultural uses, including domestic livestock grazing, that do not conform to those in practice in the historic period of the area are permitted where they contribute to the maintenance of a historic scene, are sanctioned by law, or are incidental to visitor use. Where grazing has been permitted and its continuation is not specifically covered by the aforestated conditions, it should be eliminated through orderly and cooperative procedures with the individuals concerned.

Grazing by Service or concessioner pack-and-saddle stock may be permitted, also, where it contributes to the maintenance of a historic scene; otherwise, it should be limited to those locations where dry feeding is clearly impracticable.


Woods, forests, and individual specimen trees contributing to the historical integrity of a historical area should be managed intensively to maintain the historic scene. Cutting of trees as "living history," as at Hopewell Village, should be encouraged. Trees that pose a safety hazard should be removed. Diseased, dying, or dead trees that threaten to disturb the ecology of the area may be removed provided the total ecological effects of removal will be more desirable than other management actions could produce. Every effort, however, should be made to extend the lives of specimen trees dating from the historic period of a historical area.


Visitor facilities should be planned, designed and located so as to cause the least possible disturbance to and intrusion on the historic features and the historic scene. Where such facilities already exist as intrusions, their removal should be accomplished as soon as feasible.


To achieve the purpose of a historical area, i.e., preservation and appropriate public use, planning and management should be related to the total environment in which the area is located. Such planning and management recognizes the need for transportation arteries, utility and communication corridors, consumptive resource uses, and residential, commercial, and recreation land uses in the environs of the park as parts of a systematic plan assuring viability and good health of the park and the surrounding region.

The Service should be alert to peripheral use and development proposals that impinge on the environment of a historical area. Moreover, it should cooperate with and encourage joint and regional planning among public agencies, organizations, and individuals having responsibility for maintaining the quality and aesthetics of the environment surrounding historical areas.


The Service will cooperate in the programs and purposes of historic districts, particularly in urban areas, to encourage the preservation of an environment compatible in character, texture, and productive use with the historic resources of the area.


The Service seeks to cooperate with municipal planning commissions, zoning boards, and other agencies to the extent compatible with the purposes of a historical area in order to promote a viable, orderly environment of which the area is an integral part.


Living historical interpretation, costumed guides, authentic craft demonstrations, firing of historic small arms and cannon, use of agricultural and industrial implements and practices, and the like, are encouraged.


Use of historic structures for meetings, concerts, and social gatherings helps to deepen the cultural value of the physical structures and gives visitors a more intimate feeling of continuity between the present and the past. Such uses are to be encouraged when compatible with the primary purpose of the area. All traditional and modern communication techniques, including the use of period costumes, living farms, and other demonstrations, may be employed to enhance visitor interest, enjoyment, and understanding of the Nation's history. Historic structures may be used for appropriate meetings, concerts, dances, social gatherings, celebrations, and the like, consistent with the historical values of the park. Except when such activities have a direct interpretive or traditional role, they must be scheduled to avoid the hours of maximum visitor use.

Historic structures may also be utilized for commercial and residential purposes, when compatible with the primary purpose of the area.

Reasonable fees may be charged for the use of facilities.

National Park Service, Washington, D.C.: GPO, 1968, 19-28.

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Last Modified: October 25, 2000 10:00:00 am PST

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