IV. HOW TO EVALUATE AND DOCUMENT NATIONAL SIGNIFICANCE FOR POTENTIAL NATIONAL HISTORIC LANDMARKS

Potential NHLs are evaluated for their national significance according to a set of criteria that is different from the more familiar National Register criteria. In preparing a nomination of a property for National Historic Landmark designation, the following guidelines should be considered. Claims for national significance should be supported by presenting a historical summary and reasoned comparison of the property to themes of national importance and to similar properties nationwide. In order to establish the relative merit of the proposed property, it generally should be compared not only to properties already identified as nationally significant in the same theme (i.e., existing NHLs or units of the National Park System), but also should take into consideration all similar properties not yet recognized by NHL designation or NPS authorization.

Establishing national significance requires the examination of the theme in which the property is significant to the extent necessary to document that the property represents an important aspect of the theme on a national level and is outstanding in its representation. A property should also be exceptionally important compared to similar properties within that theme. Not every residence of a nationally prominent person is a strong candidate; only the one with the strongest association is likely to be designated. Similarly, only the finest or the most influential works by a master American architect are likely to be designated NHLs.

Canterbury Shaker Village, Canterbury, New Hampshire. Shakers were the most numerous, most successful and best known of America's 19th century utopian communal societies. Canterbury, designed, built and inhabited from its founding in 1792 until the 1990s, is considered among the most intact and authentic of the Shakers surviving villages.

The areas of national significance for a property may differ from those of local and state significance. For example, a hospital may be important nationally, statewide, and locally in the history of medicine, but only have local architectural significance.

Explanation of NHL Criteria

The following discussion is arranged by each NHL criterion and explains each criterion in more detail.

NHL Criterion 1:

Properties that are associated with events that have made a significant contribution to, and are identified with, or that outstandingly represent, the broad national patterns of United States history and from which an understanding and appreciation of those patterns may be gained.

The events associated with the property must be outstandingly represented by that property and the events be related to the broad national patterns of U.S. history. Thus, the property?s ability to convey and interpret its meaning must be strong and definitive and must relate to national themes. The property can be associated with either a specific event marking an important moment in American history or with a pattern of events or a historic movement that made a significant contribution to the development of the United States.

The property that is being evaluated must be documented, through accepted means of historical or archeological research, to have existed at the time of the event or pattern of events and to have been strongly associated with those events. A property is not eligible if its associations are merely speculative. Mere association with historic events or trends is not enough to qualify under this criterion. The property's specific association must be considered of the highest importance.

Criterion 1: Events

Rohwer Relocation Center Cemetery, Desha County, Arkansas Following the dictates of Executive Order 9066 that directed the relocation of more than 110,000 Japanese aliens and Japanese-Americans, ten relocation camps were established. Rohwer, the most intact camp remaining, was constructed in 1942 and during its three-year existence housed over 10,000 evacuees. Memorials to those who died here provide a poignant record of a troubled period in American history.

Bodie Historic District, Bodie, California Gold was discovered here on the western slope of the Sierra Nevada in 1859, and by 1880 the town had a population of 10,000. The townsite was abandoned in the 1940s, and today this is considered one of the finest examples of a mining "ghost town" in the West.

NHL Criterion 2:
Properties that are associated importantly with the lives of persons nationally significant in the history of the United States.

Leap-the-Dips, Altoona, Pennsylvania, Constructed in 1902 at Lakemont Park, Leap-the-Dips is the last known extant example of a Side-Friction Figure Eight roller coaster. This represents a significant development in the technological evolution of roller coasters which had developed in tandem with amusement parks in the late 19th and early 20th centuries.

This criterion relates to properties associated with individuals whose specific contributions to American history can be identified and documented. The person(s) associated with the property must be individually exceptionally significant within a national historic context. The association must be with the person's productive life, reflecting the time period when he or she achieved significance. Properties that pre- or post-date an individual's significant accomplishments are usually not eligible. The individual's association with the property must be documented by accepted methods of historical or archeological research.

Generally, each property associated with an important individual must be compared to other associated properties to identify the one that best represents the person's nationally historic contributions, and those comparisons must be documented. The length of association is often an important factor when assessing several properties with similar historically important associations.

Criterion 2: Jackson Pollock House and Studio, East Hampton, New York Pollock, shown here at work, is considered to be one of the most revolutionary figures in the history of twentieth-century art. He lived in a house in East Hampton and worked in its backyard studio, a former barn that he had moved to the site. It was here, from 1945 until his death in 1956, that he mastered the technique of pouring and propelling paint through the air.

Criterion 2: Jackson Pollock House and Studio, East Hampton, New York Pollock, shown here at work, is considered to be one of the most revolutionary figures in the history of twentieth-century art. He lived in a house in East Hampton and worked in its backyard studio, a former barn that he had moved to the site. It was here, from 1945 until his death in 1956, that he mastered the technique of pouring and propelling paint through the air.

Criterion 2: Jackson Pollock House and Studio, East Hampton, New York. Pollock is considered to be one of the most revolutionary figures in the history of twentieth-century art. He lived in a house in East Hampton and worked in its backyard studio, a former barn that he had moved to the site. It was here, from 1945 until his death in 1956, that he mastered the technique of pouring and propelling paint through the air.

Criterion 2: Jackson Pollock House and Studio, East Hampton, New York Pollock is considered to be one of the most revolutionary figures in the history of twentieth-century art. He lived in a house in East Hampton and worked in its backyard studio, a former barn that he had moved to the site. It was here, from 1945 until his death in 1956, that he mastered the technique of pouring and propelling paint through the air.

NHL Criterion 3:
Properties that represent some great idea or ideal of the American people. This criterion relates to properties that express some great overarching concept or image held by the population of the United States. It could be a general historical belief, principle, or goal. The application of this criterion clearly requires the most careful scrutiny and would apply only in rare instances involving ideas and ideals of the highest order in the history of the United States. For example, the Brown Chapel A.M.E. Church, in Selma, Alabama, was designated under this criterion because of the role it played in the events that led to the adoption of the Voting Rights Act of 1965 and the ideal of democratic, representative government in the United States.

Criterion 3: Brown Chapel African Methodist Episcopal Church, Selma, Alabama As headquarters of the Selma Voting Rights Movement and the starting point for three Selma-to-Montgomery marches, this church played a major role in events that led to the adoption of the Voting Rights Act of 1965. The right to vote and to participate in representative government is a primary ideal of the American people making this property significant for criterion 3.

NHL Criterion 4:

Properties that embody the distinguishing characteristics of an architectural type specimen exceptionally valuable for a study of a period, style, or method of construction, or that represent a significant, distinctive and exceptional entity whose components may lack individual distinction.

This criterion's intent is to qualify exceptionally important works of design or collective elements of design extraordinarily significant as an ensemble, such as a historic district. It applies to properties significant for their physical design or construction, including such elements as architecture, landscape architecture, and engineering. The property must clearly illustrate the physical features or traits that commonly recur in individual types, periods or methods of construction. A property also must clearly contain enough of those characteristics to be considered one of the best representatives of a particular type, period, or method of construction. (Characteristics can be expressed in terms such as form, proportion, structure, plan, style, or materials.) A building or structure is a specimen of its type or period of construction if it is an exceptionally important example (within its context) of design or building practices of a particular time in history. The language is restrictive in requiring that a candidate be "a specimen exceptionally valuable for the study of a period, style, or method of construction" rather than simply embodying distinctive characteristics of a type, period, or method of construction. With regard to historic districts, an entity must be distinctive and exceptional. This criterion will not qualify all of the works of a master, per se, but only such works that are exceptional or extraordinary. Artistic value is considered only in the context of history's judgment in order to avoid current conflicts of taste.

Criterion 4: Residential Architecture

Susan Lawrence Dana House, Springfield, Illinois In pristine condition and retaining much of its original furniture and stained glass, this house is one of the masterpieces of architect Frank Lloyd Wright's early period.

Riversdale, Riverdale, Maryland Constructed of stuccoed brick and dating from the beginning of the nineteenth century, this house is one of the last of Maryland's great five-part Palladian mansions.

Bellevue, LaGrange, Georgia Built in the 1850s by Georgia statesman Benjamin Harvey Hill, this house is a perfect high-style expression of the Greek Revival at the height of antebellum Southern affluence.

Kingscote, Newport, Rhode Island Begun in 1839, this frame Gothic Revival house is one of Newport's oldest summer "cottages." It helped promote the cause of romantic design across the country and the careers of its architect, Richard Upjohn, and its landscape architect, Andrew Jackson Downing.

Philip Johnson's Glass House, New Canaan, Connecticut This 1949 house is one of the masterworks of modern American architecture and epitomizes the International Style.

Stanley-Whitman House, Farmington, Connecticut This classic New England saltbox house dates from 1720, but incorporates earlier features typical of late 17th-century work.

Criterion 4: Commercial Architecture

Wainwright Building, St. Louis, Missouri Built in 1890-91, from designs by Louis Sullivan, this ten-story, iron-and-steel framed office building was pivotal in the history of tall-building design and construction.

Marin County Civic Center, San Raphael, California One of the finest expressions of Frank Lloyd Wright's "organic architecture," this monumental, dramatically-sited governmental complex was the last major work of the great architect.

NHL Criterion 5:

Properties that are composed of integral parts of the environment not sufficiently significant by reason of historical association or artistic merit to warrant individual recognition but collectively compose an entity of exceptional historical or artistic significance, or outstandingly commemorate or illustrate a way of life or culture.

This criterion is meant to cover historic districts such as Williamsburg, Virginia; New Bedford, Massachusetts; or Virginia City, Nevada, which qualify for their collective association with a nationally significant event, movement, or broad pattern of national development. Most historic districts that are nationally significant for their extraordinary historic importance, rather than for their architectural significance, are recognized by this criterion.

Deadwood Historic District, Deadwood, South Dakota Reflecting collective entities and historic districts which qualify for their collective association with a nationally significant event, movement or broad pattern of national development, Deadwood still retains a number of buildings dating from its heyday in the 1880s and 1890s and maintains the atmosphere of a western mining town.

Crow Island School, Winnetka, Illinois Jointly designed by Eliel and Eero Saarinen and Perkins, Wheeler, and Will, this seminal International- style building opened in 1940 and served as the prototype for elementary schools across the country.

NHL Criterion 6:

Criterion 5: Cannelton Cotton Mill, Cannelton, Indiana The work of Rhode Island architect Thomas A. Tefft, who combined utility and aesthetics in his design, this was one of the most impressive pre-Civil War mills in the Midwest.

Properties that have yielded or may be likely to yield information of major scientific importance by revealing new cultures, or by shedding light upon periods of occupation over large areas of the United States. Such sites are those which have yielded, or which may reasonably be expected to yield, data affecting theories, concepts and ideas to a major degree.

Criterion 6 was developed specifically to recognize archeological properties, all of which must be evaluated under this criterion. Properties being considered under this criterion must address two questions:

1) what nationally significant information is the site likely to yield? and
2) is the information already produced nationally important?

Answers to both questions must be well documented and logically organized. In order to establish the national significance of an archeological resource, it must be demonstrated how the data has made or will make a major contribution to the existing corpus of information. This criterion requires that potentially recoverable data are likely to substantially modify a major historic concept, resolve a substantial historical or anthropological debate, or close a serious gap in a major theme of American history. It is necessary to be explicit in demonstrating the connection between the important information and a specific property. The discussion of the property must include the development of specific important research questions which may be answered by the data contained in the property. Research questions can be related to property-specific issues, to broader questions about a large geographic area, or to theoretical issues independent of any particular geographic location.

Criterion 6: Huff Archeological Site, Morton County, North Dakota Located on the Missouri River, this village site is one of the best-known and best preserved sites of the Mandan people. Remains of a bastioned fortification system and a dense and regular arrangement of houses, plus a wide variety of material culture attest to the Mandan way of life in such villages by ca. 1500 A.D.

The current existence of appropriate physical remains must be ascertained in considering a property?s ability to yield important information. Properties that have been partly excavated or otherwise disturbed and that are being considered for their potential to yield additional important information must be shown to retain that potential in their remaining portions.

Properties that have yielded important information in the past and that no longer retain additional research potential (such as completely excavated archeological sites) must be assessed essentially as historic sites under Criterion 1. Such sites must be significant for associative values related to:

1) the importance of the data gained or

2) the impact of the property?s role in the history of the development of anthropology/ archeology or other relevant disciplines.

The following discussion is arranged by each NHL criteria exception and explains each exception in more detail.

NHL Exception 1:

A property owned by a religious institution or used for religious purposes would qualify if the property derives its primary national significance from architectural or artistic distinction or historical importance.

A religious property requires justification on architectural, artistic, or historical grounds to avoid any appearance or judgment by the government about the endorsement of any religion or belief. If the property is nationally significant for its architectural design or construction, it should be evaluated within an established architectural context, and compared to other properties of its type, period, or method of construction. A religious property can also be eligible if it is directly associated with either a specific event or a broad pattern that is nationally significant in another historic context, or a specific event or a broad pattern in the history of religion. Individuals who were nationally significant by virtue of their formation of or significant influence on an important religious institution or movement, or who were important in the social, economic, or political history of the nation may also qualify a religious property for designation. This exception must be considered if:

1) the resource was constructed by a religious institution;
2) the resource is presently owned by a religious institution or is used for religious purposes; or
3) the resource was owned by a religious institution or used for religious purposes during its period of significance.

Exception 1: New St. Mary's Episcopal Church, Burlington, New Jersey New St. Mary's is a pivotal building in the history of the Gothic Revival style as it was the first American attempt to imitate a specific English medieval church. Its design and construction were milestones in the career of Richard Upjohn and therefore, it is eligible under the criteria exception for religious properties because its primary significance is for its architectural or artistic distinction.

NHL Exception 2:

A building or structure that has been moved from its original location, but which is nationally significant primarily for its architectural merit, or for its association with persons or events of transcendent importance in the nation's history and the association is consequential, would qualify for designation.

Because national significance is embodied in locations and settings as well as in the properties themselves, moving a property usually destroys the relationships between the property and its surroundings and usually destroys associations with historic events and persons. If the moved property is nationally significant for its architectural merit, it must retain enough historic features to convey its architectural values and retain integrity of design, materials, workmanship, feeling, and association. If the moved property is nationally significant for its associations with persons or events of transcendent importance, it must be demonstrated that this property is the only surviving property most importantly associated with a particular nationally significant historic event or an important aspect of a nationally significant person's life. However, the use of the word transcendent indicates that the person or event must have a level of national significance which is greater than that which would ordinarily qualify a person or event to be nationally significant. In addition, the property must be the single surviving property that is most closely associated with the event or with the part of the person's life for which he or she is nationally significant.

Moved properties must still have an orientation, setting, and general environment that are comparable to those of the historic location and that are compatible with the property's significance. A rural house that is moved into an urban area or an urban property moved into a rural setting or a bridge, originally built over water, that is no longer situated over a waterway would not meet this exclusion.

Exception 2: Block Island Southeast Light, Block Island, Rhode Island A major aid to navigation since it was first lit in 1874, this lighthouse tower and attached keeper's house sit atop Mohegan Bluff and are visible for miles along a busy sea lane. When the structures became threatened with collapse by continual erosion of the bluff, they had to be moved some 360 feet in August 1993. This property still has the orientation, setting, and general environment comparable to that of its historic location and are compatible with its significance.

A property designed to be moved or a property frequently moved during its historic use must be located in a historically appropriate setting in order to qualify, retaining its integrity of setting, design, feeling, and association. Such properties include ships, railroad cars and engines, airplanes, and other passenger vehicles.

NHL Exception 3:
A site of a building or structure no longer standing would qualify if the person or event associated with it is of transcendent importance in the nation's history and the association is consequential.

The nomination must demonstrate that the person or event associated with the site of a building or structure no longer standing is of a level of national significance greater than that which would ordinarily qualify a person or event to be nationally significant. In addition, that association to the property must be demonstrated to have been consequential rather than a connection that was incidental and of little impact on either the event or the reason for the person to be considered of exceptional national significance. This exception is rarely met.

Exception 3 (top): W.E.B. DuBois Boyhood Homesite, Great Barrington, Massachusetts As a major figure in the Civil Rights Movement during the first half of the twentieth century who helped found the NAACP, prominent sociologist and writer William Edward Burghardt DuBois is a figure of transcendent importance in the nation's history. Although only ruins mark the site of his boyhood home, DuBois owned the house on the site from 1928 to 1954 making his association with the site consequential.

NHL Exception 4:

A birthplace, grave, or burial would be considered for designation if it is for a historical figure of transcendent national significance and no other appropriate site, building or structure directly associated with the productive life of that person exists.

The lives of persons nationally significant in the nation's past normally are recognized by the designation of properties illustrative of or associated with their productive lives. Birthplaces and graves, as properties that represent the beginning and the end of the life of important individuals, may be temporally and geographically far removed from their nationally significant activities, and therefore are not usually considered eligible. To qualify, the birthplace or grave must be the birthplace or grave of a person with a level of national significance greater than that which would ordinarily qualify a person to be nationally significant. In addition to the person being of outstanding national significance, the site must be the last surviving property associated with the person. When all other properties directly associated with his or her productive life are gone or have lost integrity, a birthplace or grave may be eligible for designation.

A birthplace or grave may also be eligible if they are nationally significant for reasons other than associations with the person in question. It could be considered for association with important event(s) (Criterion 1) such as the Haymarket Martyrs? Monument in Forest Park, Illinois, or for architectural significance (Criterion 4). In very rare cases, a birthplace or grave could also be eligible if, after the passage of time, it is significant for its commemorative value. (See discussion on Exception 7, Commemorative Properties)

Properties that must meet this criteria exception are birthplaces of nationally significant persons who lived elsewhere during their period of significance, or a grave that is nominated for its association with the significant person buried in it. If the birthplace is the location of the nationally significant person's productive contributions, or if the grave is located on the grounds of a property where the nationally significant person spent his or her productive years, then the property does not need to meet this exception.

Exception 4 (center): Ivy Green (Helen Keller Birthplace), Tuscumbia, Alabama Born in this cottage, Helen Keller, left blind and deaf at an early age, learned to communicate, thanks to the unceasing efforts of Anne Sullivan, at a water pump on the property. Going on to teach and inspire humanity throughout the world, Helen Keller became a figure of transcendent national significance. Through all of her later schooling and travels on behalf of the deaf and blind, no place represented long-term stability as much as Ivy Green.

NHL Exception 5:

A cemetery would be eligible if it derives its primary national significance from graves of persons of transcendent importance, or from an exceptionally distinctive design or from an exceptionally significant event.

A cemetery is defined as a collection of graves that is marked by stones or other artifacts or that is unmarked but is recognizable by features such as fencing or depressions, or through maps, or by means of archeological testing. A cemetery which contains the graves of persons of a level of national significance greater than that which would ordinarily qualify a person to be nationally significant may be eligible for designation. These persons must have been of great eminence in their fields of endeavor or had a nationally significant impact upon the nation's history.

Cemeteries may also qualify based on distinctive design values. These are the same values which are addressed in Criterion 4 and could include aesthetic or technological achievement in the fields of landscape architecture, city planning, architecture, art, sculpture, or engineering. As for all other properties being considered under Criterion 4, a cemetery must clearly express its design values and be able to convey its historic appearance, such as Laurel Hill Cemetery in Philadelphia, Pennsylvania. A cemetery associated with nationally significant historic events which could include either a specific important event or general events which illustrate broad patterns could also be considered for designation.

A cemetery that is nominated with its associated church when the church is the main resource nominated does not need to meet this exception. In addition, a cemetery does not need to meet the exception if it is nominated as part of a district but is not the focal point of the district.

Exception 5 (bottom): Laurel Hill Cemetery, Philadelphia, Pennsylvania One of America's oldest "romantic" cemeteries, Laurel Hill was designed by John Notman in 1835-36. It was intended to be a place where mourners and tourists could seek comfort and solace not only from their grief, but also from the increasing urbanism all around them. With its winding walkways and landscaped grounds, its distinctive design was cited as a model for large urban parks.

NHL Exception 6:

A reconstructed building or ensemble of buildings would qualify if the buildings are of extraordinary national significance and are accurately executed in a suitable environment and presented in a dignified manner as part of a restoration master plan, and when no other buildings or structures with the same association have survived.

A reconstruction is defined as the reproduction of the exact form and detail of a vanished building, structure, or object, or a part thereof, as it appeared at a specific period of time. The reconstruction may be wholly constructed of new materials or may be reassembled from some historic and some new materials.

The event, person, movement, or style that the property is significant for must be of a level of national significance greater than that which would ordinarily qualify a person, event, movement, or style to be nationally significant. When all other properties directly associated with the event or person are gone or have lost integrity, a reconstruction also may be eligible.

In addition, the reconstruction must be based upon sound archeological, architectural, and historic data concerning the historic construction and appearance of the resource. That documentation should include both analysis of any above or below ground material and research in written and other records. The reconstructed property must be located at the same site as the original and must also be situated in its original grouping of buildings, structures, and objects (as many as are extant), and that grouping must retain integrity. In addition, the reconstruction must not be misrepresented as an authentic historic property. The reconstructed property should also be an essential component in a historic district and the reconstruction part of an overall restoration plan for the entire district.

Exception 6 (top): Williamsburg Historic District, Williamsburg, Virginia As capital of the largest English colony in America, Williamsburg was influential in many of the events that led to the Revolution and American independence. Once the capitol moved to Richmond in 1780, the city remained in obscurity until the 1920s when John D. Rockefeller sponsored the restoration and rebuilding of the entire colonial capital. As a milestone in historic preservation, Williamsburg's staff continues to refine the definitions of restoration.

After the passage of fifty years, a reconstruction may on its own attain national significance for what it reveals about the period in which it was built, rather than the historic period it was intended to depict. A reconstruction may then be eligible if it addresses the particular criteria for which it has now attained national significance.

NHL Exception 7:

A property that is primarily commemorative in intent may be eligible if design, age, tradition, or symbolic value has invested it with its own national historical significance.

Commemorative properties are designed or constructed after the occurrence of an important historic event or after the life of an important person. They are not directly associated with the event or with the person's productive life, but serve as evidence of a later generation's assessment of the past. Their significance comes from their value as cultural expressions at the date of their creation.

A commemorative property must be over 50 years old and must possess significance based on its own value, not on the value of the event or person being memorialized. The Haymarket Martyrs? Monument is an example of this criterion exception. A commemorative property's design often represents the aesthetic values of the period of its creation. The property, therefore, may be nationally significant for the architectural, artistic, or other design qualities of its own period in history. In this case, the property should be evaluated within an established national architectural, artistic, or construction context, and compared to other properties of its type, period, or method of construction.

A commemorative property may also acquire national significance after the time of its creation through age, tradition, or symbolic value. In this case, the property must be nationally significant under one of the criteria and the national significance must be documented by accepted methods of historical research.

Exception 7: John Brown Farm and Gravesite, Lake Placid, New York John Brown's body was returned here for burial, at his request, after he was tried for treason and executed in 1859 for his attempt to exorcize slavery from America by armed confrontation. The site was regarded as a shrine from the moment he was interred and many pilgrimages were made to see the grave. This symbolic value has invested the site with its own national significance.

A commemorative marker erected to memorialize a nationally significant person, event, or movement in the nation's history would not be eligible simply for its association with the person, event, or movement it memorialized. Neither is the case strengthened for the consideration of a commemorative property by the loss of other properties directly associated with a significant event or person. The commemorative property does not have direct historical association.

A single marker that is a component of a district does not need to meet this criteria exception.

NHL Exception 8:

A property achieving national significance within the past 50 years may be eligible if it is of extraordinary national importance.

Fifty years is a general estimate of the time needed to develop historical perspective and to evaluate national significance. A property that has achieved national significance within the last 50 years can be evaluated only when sufficient historical perspective exists to determine that the property has a level of national significance greater than that which would ordinarily qualify a person or event to be nationally significant. The necessary perspective can be provided by scholarly research and evaluation, and must consider both the national historic context and the specific property's role in that context.

Exception 8: Air Force Facility Missile Site 8, Green Valley, Arizona Less than 50 years ago (between 1963 and 1987), fifty-four Titan II Intercontinental Ballistic missile (ICBM) complexes, designed to survive a first-strike nuclear attack and launch warheads, were constructed and placed "on alert." Because these weapons were America's response to the "missile gap" panic of the Cold War of the late 1950s and early 1960s, they are of extraordinary national importance

A property that begins its period of national significance more than fifty years before the nomination but continues to achieve national significance into a period less than fifty years before the nomination must meet this exception. In addition, a property that is more than fifty years old but whose nationally significant associations or qualities are less than fifty years old must also meet the exception.

A historic district in which a few properties are less than fifty years old, but the majority of properties and their nationally significant period of significance are greater than fifty years old, does not need to meet this exception.

Defining a High Degree of Integrity

Integrity is the ability of a property to convey its historical associations or attributes. The evaluation of integrity is somewhat of a subjective judgment, but it must always be grounded in an understanding of a property's physical features and how they relate to its historical associations or attributes. The NHL Survey recognizes the same seven aspects or qualities of integrity as the National Register. These are location, design, setting, materials, workmanship, feeling, and association.

• Location is the place where the historic property was constructed or the place where the historic event occurred. The actual location of a historic property, complemented by its setting, is particularly important in recapturing the sense of historic events and persons.
• Design is the combination of elements that create the historic form, plan, space, structure, and style of a property. This includes such elements as organization of space, proportion, scale, technology, ornamentation, and materials. Design can also apply to districts and to the historic way in which the buildings, sites, or structures are related. Examples include spatial relationships between major features; visual rhythms in a streetscape or landscape plantings; the layout and materials of walkways and roads; and the relationship of other features, such as statues, water fountains, and archeological sites.
• Setting is the physical environment of a historic property. It refers to the historic character of the place in which the property played its historical role. It involves how, not just where, the property is situated and its historical relationship to surrounding features and open space. The physical features that constitute the historic setting of a historic property can be either natural or manmade and include such elements as topographic features, vegetation, simple manmade paths or fences and the relationships between buildings and other features or open spaces.
• Materials are the physical elements that were combined or deposited during a particular period of time and in a particular pattern or configuration to form a historic property. If the property has been rehabilitated, the historic materials and significant features must have been preserved. The property must also be an actual historic resource, not a re-creation; a property whose historic features have been lost and then reconstructed is usually not eligible.
• Workmanship is the physical evidence of the crafts of a particular culture or people during any given period in history. It is the evidence of artisans' labor and skill in constructing or altering a building, structure, object, or site. It may be expressed in vernacular methods of construction and plain finishes or in highly sophisticated configurations and ornamental detailing. Examples of workmanship in historic buildings include tooling, carving, painting, graining, turning, and joinery. Examples of workmanship in precontact contexts include Paleo-Indian Clovis points, Archaic period beveled adzes, Hopewellian worked bone pendants, and Iroquoian effigy pipes.
• Feeling is a property's expression of the aesthetic or historic sense of a particular period of time. It results from the presence of physical features that, taken together, convey the property's historic character. For example, a rural historic district which retains its original design, materials, workmanship, and setting will relate the feeling of agricultural life in the 19th century.
• Association is the direct link between an important historic event or person and a historic property. A property retains association if it is the place where the event or activity occurred and is sufficiently intact to convey that relationship to an observer. Therefore, a property where a nationally significant person carried out the action or work for which they are nationally significant is preferable to the place where they returned to only sleep, eat or spend their leisure time. Like feeling, association requires the presence of physical features that convey a property's historic character.

For NHL designation, a property should possess these aspects to a high degree. The property must retain the essential physical features that enable it to convey its historical significance. The essential physical features are those features that define both why a property is significant (NHL criteria and themes) and when it was significant (periods of significance). They are features without which a property can no longer be identified as, for instance, a late 19th century dairy barn or an early 20th century commercial building. To assess integrity one must

1) define the essential physical features that must be present to a high degree for a property to represent its significance;
2) determine whether the essential physical features are apparent enough to convey the property?s significance; and
3) compare the property with similar properties in the nationally significant theme.

A property that is significant for its historical association should retain the essential physical features that made up its character or appearance during the period of its association with the important event, historical pattern, or person(s). If the property is a site where there are no material cultural remains, such as a battlefield, the setting must be intact. If the historic building associated with the event, pattern, or person no longer exists, the property has lost its historical integrity.

A property important for illustrating a particular architectural style or construction technique must retain the physical features that constitute that style or technique. A property that has lost some historic materials or details can be considered if it retains the majority of the features that illustrate its style in terms of the massing, spatial relationships, proportion, pattern of windows and doors, texture of materials, and ornamentation. A property should not be considered if it retains some basic features conveying massing but has lost the majority of the features that once characterized its style.

For properties to be considered under Criterion 6, integrity is based upon the property's professionally demonstrated intactness of archeological deposits and features. These are important for identifying whether a site has the potential to yield data that may address nationally significant research questions.

Properties being considered under Criteria 1 through 5 must not only retain the essential physical features, but the features must be visible enough to convey their significance and historic identity. This means that even if a property is physically intact, its integrity is questionable if its significant features are concealed under modern construction. Archeological properties are the exception to this; by nature they may not require visible features to convey their significance.