<P> The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation for their historical significance . A property listed in the National Register, or located within a National Register Historic District, may qualify for tax incentives derived from the total value of expenses incurred preserving the property . </P> <P> The passage of the National Historic Preservation Act (NHPA) in 1966 established the National Register and the process for adding properties to it . Of the more than one million properties on the National Register, 80,000 are listed individually . The remainder are contributing resources within historic districts . </P> <P> For most of its history the National Register has been administered by the National Park Service (NPS), an agency within the United States Department of the Interior . Its goals are to help property owners and interest groups, such as the National Trust for Historic Preservation, coordinate, identify, and protect historic sites in the United States . While National Register listings are mostly symbolic, their recognition of significance provides some financial incentive to owners of listed properties . Protection of the property is not guaranteed . During the nomination process, the property is evaluated in terms of the four criteria for inclusion on the National Register of Historic Places . The application of those criteria has been the subject of criticism by academics of history and preservation, as well as the public and politicians . </P> <P> Occasionally, historic sites outside the country proper, but associated with the United States (such as the American Embassy in Tangiers) are also listed . Properties can be nominated in a variety of forms, including individual properties, historic districts, and multiple property submissions (MPS). The Register categorizes general listings into one of five types of properties: district, site, structure, building, or object . National Register Historic Districts are defined geographical areas consisting of contributing and non-contributing properties . Some properties are added automatically to the National Register when they become administered by the National Park Service . These include National Historic Landmarks (NHL), National Historic Sites (NHS), National Historical Parks, National Military Parks / Battlefields, National Memorials, and some National Monuments . (Federal properties can be proclaimed National Monuments under the Antiquities Act because of either their historical or natural significance . They are managed by multiple agencies . Only monuments that are historic in character and managed by the National Park Service are listed administratively in the National Register .) </P>

The national register of historic places is maintained by