National Park Service Affiliated Areas: An Overview

In addition to managing the 433 units of the National Park System, the National Park Service (NPS) manages or assists with other areas that are linked in importance and purpose to this system. These related areas may be recognized by Congress and may receive assistance from NPS but typically are owned and administered primarily by nonfederal entities. Among these related areas are 32 sites that NPS has classified under the title of affiliated areas. NPS defines affiliated areas as locations that "preserve significant properties outside the National Park System … [and that] draw on technical or financial aid from the National Park Service" (National Parks: Index 2012-2016, p. 118).

History of Affiliated Area Status

The standard by which NPS categorizes affiliated areas has evolved over the years. In 1953, Congress passed legislation distinguishing between the "National Park System" and "miscellaneous areas administered in connection therewith"—that is, those properties not directly managed by NPS but over which NPS exercised some administrative responsibilities through cooperative agreements (August 8, 1953; 67 Stat. 496). In 1970, however, Congress removed references to such "miscellaneous areas" (P.L. 91-383) and amended the definition of national park system to include all lands and waters "administered by" NPS. In 1975, NPS issued the National Parks: Index (an official list of system areas that NPS publishes from time to time), in which the agency classified nine sites under the new designation of affiliated areas, citing the 1970 amendments as the need for this new classification for sites "not officially recognized as units of the National Park System itself." In the years following, NPS published updated versions of the National Parks: Index, each including a list of sites categorized under the affiliated area designation. Despite this, in the years following, there was little consistency in how NPS determined which sites fell into this category. For example, sometimes the affiliated category included designations such as national heritage areas and trails in the National Trails System; at other points, NPS excluded these areas from the affiliated category.

In 1988, Congress passed legislation directing NPS to deliver a report defining the "criteria for the elements of national significance and other factors necessary for a proposed area to be considered appropriate for inclusion as an affiliated area" (P.L. 100-336). Later that year, NPS proposed revised management policies that would have created such criteria. The proposed policies described affiliated areas as "a small group of nationally significant areas … protected and managed by other organizations and agencies but [that] have some formal financial or legal relationship with the National Park Service" (53 Federal Register 32115). NPS specified that, to be eligible for affiliated status, "areas must meet the same criteria for national significance as national landmarks or potential units of the national park system." At that time, NPS did not finalize the proposed management policies.

In 1990, NPS delivered a report to Congress, pursuant to P.L. 100-336, outlining some of the difficulties in classifying areas where NPS does not directly administer the area but has some special cooperative arrangement: "Areas have been classified as affiliated because they did not fit the definition of a park system unit rather than because they did meet some clearly defined criteria," the report stated. In turn, the report recommended that Congress recognize the affiliated area category and endorse the criteria set forth by NPS in the report, which largely replicated the 1988 proposed policies. To date, Congress has not established a legal definition or criteria for the affiliated area status.

Designation Criteria

In August 2006, NPS finalized its current policy manual, which included eligibility criteria for affiliated area status (NPS Management Policies 2006, §1.3.4). These criteria are similar to those proposed by NPS in 1988 and 1990. To be eligible, proposed areas must

• meet the same standards for significance and suitability that apply to units of the National Park System;
• require special recognition or technical assistance beyond what is available through existing NPS programs;
• be managed in accordance with the policies and standards that apply to units of the system; and
• be assured of sustained resource protection, as documented in a formal agreement between NPS and the management entity.

Designation Process

Sites designated as affiliated areas have been established legislatively through acts of Congress, as well as administratively, generally by the Secretary of the Interior (Interior) under the authority of the Historic Sites Act of 1935 (54 U.S.C. §§320101 et seq.). Some designations predate the usage of the term "affiliated area," whereas others, generally starting the late 1990s, were specifically categorized as affiliated areas upon designation. Affiliated areas carry no standard naming convention and instead have been established with varying titles (e.g., national memorial, national historic site); but most designations establish certain administrative and management responsibilities for NPS in partnership with a nonfederal entity. More than half of the 32 affiliated areas were established legislatively through acts of Congress.

The earliest-designated existing affiliated area is the Jamestown National Historic Site. The site was designated on December 18, 1940, by an administrative action in which the Secretary called for "a unified program of development and administration" between NPS and the Association for the Preservation of Virginia Antiquities. The association continues to own and operate this site. The most recent sites established as affiliated areas are five current and former schools in Delaware, Virginia, and the District of Columbia, associated with the Brown v. Board of Education National Historical Park. Congress authorized the establishment of these areas in 2022, following the identification by the Secretary of an "appropriate management entity" for each site (P.L. 117-123). In January 2025, then-Secretary Haaland announced the designation of these sites as affiliated areas.

At times, Congress has designated affiliated areas following the completion of a special resource study (SRS) by NPS. Typically, NPS conducts such studies pursuant to congressional direction to determine whether a given site is an appropriate candidate for inclusion as a unit of the park system. According to P.L. 105-391, an SRS will determine whether an area (1) possesses nationally significant natural or cultural resources and (2) is a suitable and feasible addition to the system. If the study determines that an area meets the criteria for national significance but is not suitable or feasible for NPS management under unit status, NPS might recommend the site for affiliated status.

Affiliated area designation also may arise from less formal reconnaissance surveys conducted by NPS at the request of Members of Congress. Similar to an SRS, these typically are used to determine whether a given site would meet the criteria for addition to the park system and, if so, would warrant further study through a full SRS. Recently, some Members have requested that NPS conduct reconnaissance surveys to determine whether a given site would be appropriate for affiliated area status.

Some sites previously designated or categorized as affiliated areas have been removed from this classification. Sometimes this removal resulted from a shift in how NPS defined affiliated areas, as was the case with several national heritage areas and early units of the National Trails System. Other sites previously categorized as affiliated areas were redesignated as full units of the park system. For example, in 2009, Congress redesignated Port Chicago Naval Magazine National Memorial as a system unit (P.L. 111-84). In 2016, NPS acquired the Sewall-Belmont House in Washington, DC, and President Obama established the Belmont-Paul Women's Equality National Monument as a unit of the system (81 Federal Register 22503) more than 40 years after Congress had designated the site as a national historic site (P.L. 93-487).

The only site previously designated as a park system unit to be redesignated as an affiliated area is the Oklahoma City National Memorial. Congress initially authorized the site as a system unit (albeit one administered in partnership with a private entity) in 1997 (P.L. 105-58). Congress redesignated the site as an affiliated area in 2004 (P.L. 108-199).

Administration, Funding, and Ownership

Affiliated areas have varying management and funding arrangements depending on any specific enabling legislation, cooperative agreements, and/or management plans. In general, NPS is less involved in the funding and management of affiliated areas than of park system units. Typically, NPS directly administers units of the park system, whereas it provides technical and sometimes financial assistance to affiliated areas, which are administered primarily by nonfederal entities.

Federal funding for affiliated areas varies on a site-by-site basis. Congress has authorized federal funding for some affiliated areas in enabling legislation or through the annual appropriations process. Other sites receive no federal funding but receive technical assistance from NPS. In general, administratively designated sites do not receive federal funding unless Congress specifically appropriates funding for them.

The majority of affiliated areas are nonfederally owned. However, NPS does own portions of several areas, including more than 90,000 acres of the Pinelands National Reserve in New Jersey, the largest affiliated area by size.

Congressional Activity

Congress continues to consider legislation that would establish additional affiliated areas. In the 119^th Congress, legislation was introduced proposing to establish the General George C. Marshall House in Virginia (H.R. 1352/S. 603) and the Justice Thurgood Marshall National Historic Site in Maryland (H.R. 1718/S. 791) as affiliated areas. In the 118^th Congress, other bills were introduced that would have established Fort San Gerónimo del Boquerón in Puerto Rico as an affiliated area (H.R. 359) and the Grand Village of the Natchez Indians and Jefferson College as affiliated areas of the Natchez Historical Park in Mississippi (S. 3241).