Frequently Asked Questions (FAQs)

The Heritage Documentation Programs (HDP) consist of the Historic American Buildings Survey (HABS), Historic American Engineering Record (HAER), and Historic American Landscapes Survey (HALS). The programs document historic sites and structures across the United States through the creation of measured drawings, large-format photographs, and historical reports. Documentation is archived in the HABS/HAER/HALS Collection at the Library of Congress and is available to the public without restriction. HDP is part of the National Park Service’s Cultural Resources, Partnerships, and Science Directorate.

HABS/HAER/HALS documentation provides a permanent record of historic places, representing the complete breadth of American architecture, engineering, and landscape design.

The Library of Congress stores the documentation and makes it available to people around the world via its website. Researchers can also access HABS/HAER/HALS materials at the Library’s James Madison Memorial Building in Washington, DC.

HABS/HAER/HALS documentation is utilized in many ways, including in the repair or reconstruction of historic places, facilities maintenance, scholarly research, or teaching aids.

HABS/HAER/HALS documentation is archived in the Library of Congress and is available to the public without restriction. The library’s archival expertise, combined with the collection’s durable material standards, ensure that HABS/HAER/HALS documentation is preserved in perpetuity. The collection is also digitized, allowing access via the library’s website to practitioners, scholars, students, and others interested individuals throughout the world.

No. The Library of Congress is the only designated repository for HABS/HAER/HALS documentation. Surveys are not included in the HABS/HAER/HALS Collection if they are only archived at other repositories. State, local, and agency repositories are welcome to house duplicates of materials archived in the Library of Congress.

The HABS/HAER/HALS programs are authorized through Section 101 of the National Historic Preservation Act (54 U.S.C. § 302107) and Section 2 of the Historic Sites Act (54 U.S.C. § 302102).

HABS/HAER/HALS surveys come from a variety of sources. For our purposes, surveys fall into three categories:

  • Documentation created by HDP or other NPS staff members.
  • Mitigation documentation is completed to resolve adverse effects to historic properties in compliance with Section 106 of the National Historic Preservation Act.
  • Documentation donated is from a wide range of sources, including state- and city-level mitigation, competition entries, student projects, and surveys by other professionals who want to document historic places.

No. In 2016, the National Park Service issued a memorandum (pdf) clarifying that historic properties significant at the national, state, regional, and local levels are all eligible for inclusion in the HABS/HAER/HALS Collection at the Library of Congress.



The contents of a survey depend on the level of documentation, the complexity of the property, and the availability of information. Consult with the NPS staff member who is reviewing your project if you have questions about a specific survey.

The National Park Service generally reviews draft documentation prior to assigning a HABS/HAER/HALS survey number and, if needed, setting up the official title block for a sheet set. See below for contact information.

Last updated: October 30, 2023