List of national historic sites and historical parks of the United States

National Historic Sites (NHSes) and National Historical Parks (NHPs) are officially recognized areas of nationally historic significance in the United States. They are usually owned and managed by the federal government. An NHS usually contains a single historical feature directly associated with its subject, while an NHP is an area that generally extends beyond single properties or buildings to include a mix of historic and later structures and sometimes significant natural features.

There are 64 NHPs and 85 NHSes. Most NHPs and NHSes are managed by the National Park Service (NPS). Some federally designated sites are owned by local authorities or privately owned, but are authorized to request assistance from the NPS as affiliated areas. One property is managed by the U.S. Forest Service: Grey Towers National Historic Site.

Since October 15, 1966, all historic areas in the NPS, including NHPs and NHSes, are automatically listed on the National Register of Historic Places (NRHP). There are about 90,000 NRHP sites, the large majority of which are neither owned nor managed by the NPS. Of these, about 2,600 have been designated at the highest status as National Historic Landmark (NHL) sites.

After its founding in 1916, the National Park Service initially oversaw sites of primarily scenic and natural significance, including national parks and national monuments. Historians soon began recommending preservation of sites relating to human history. Congress created Colonial National Monument in 1930 to protect the Jamestown Settlement and Yorktown battlefield in Virginia as one of the first new historical areas, and it was renamed a national historical park in 1936. It then established Morristown National Historical Park, the 1779–1780 winter encampment of the Continental Army in New Jersey, on March 2, 1933, as the first NHP: The U.S. House committee noted that the new designation was logical for the area and set a new precedent, with comparison to the national military parks, which were then in the War Department. The park's establishment allowed the NPS to have an administrative historical program with professional historians. President Franklin D. Roosevelt reorganized the agency to also oversee memorials and military parks with historic significance later in 1933, substantially broadening the NPS's mandate.

In 1935, Congress passed the Historic Sites Act (Pub. L. 49–666), which established that "it is a national policy to preserve for public use historic sites, buildings and objects of national significance for the inspiration and benefit of the people of the United States." This expanded upon the Antiquities Act of 1906, which gave the President the ability to order "the protection of objects of historic and scientific interest." The Historic Sites Act directed the National Park Service to survey historic sites which may be of national significance, as well as restore and acquire properties. The Historic American Buildings Survey began to document the country's architectural heritage and identify buildings for potential protection. Initially the Secretary of the Interior could designate national historic sites, though this did not include funding for acquisition or administration without congressional action. Salem Maritime National Historic Site was the first place to be preserved as a national historic site, created by Secretary Harold L. Ickes's secretarial order on March 17, 1938. It had followed his designation of the Jefferson National Expansion Memorial in 1935; many historic sites in the National Park System continue to be protected under different designation types. Hopewell Furnace National Historic Site was designated later that year, another example of industrial heritage.

As the NPS developed criteria for nationally significant historic sites in the late 1930s, it aimed to identify unique sites that could each tell a broad story and would fit together to cover all aspects of American history. Surveys of sites were guided by themes and chronologies to ensure a diverse and comprehensive selection of those most representative of different eras and geographies, with less political influence over site selection. In the 1950s, the Mission 66 program revived historic studies that had lagged during World War II and saw the creation of the National Historic Landmarks program as a method to recognize important sites. From the 1960s to 1990s, the NPS evolved from a thematic framework, in which numerous specific themes and subthemes of American history were expected to each be included in some way in the system, to a conceptual framework, whereby both new and existing park units would be examined more holistically for ways to study history such as "creating social movements and institutions," "developing the American economy," and "peopling places." In the 20th century, potential new park units have been recommended not so much on "an orderly, balanced, and comprehensive" preservation of "outstanding examples", as Chief Historian Ronald Lee put it, but on those mandated to be studied by Congress, most of whose requests are recommended against by the NPS.

A 1973 NPS publication outlined policies for administration of historical areas, which were distinct from its natural and recreational areas. This included not only NHSes and NHPs but also national military parks, national battlefields, national battlefield parks, national battlefield sites, national memorials, and some national monuments; at that time there were 178 such areas, and management focused on "maintaining and where necessary restoring the historical integrity of structures, sites and objects significant to the commemoration or illustration of the historical story". But because most units contained a combination of natural, historic, and recreational lands, the General Authorities Act of 1970 made all areas equal within the National Park System; separate policy manuals for each were replaced in 1975 with one that would tailor policies in each park respective to the purpose of zones within.

National Historic Sites are generally federally owned and administered properties, though some remain under private or local government ownership. There are currently 85 NHSes, of which seventy-five are official NPS units, nine are NPS affiliated areas, and one is managed by the United States Forest Service.