The Historic American Engineering Record, or HAER, is the federal documentation program created to record the nation's engineering and industrial heritage. Its subjects range from bridges, roads, rail systems, and public utilities to factories, machinery, mines, ships, vehicles, and other engineered works.
HAER was founded in 1969 and is now part of the National Park Service's Heritage Documentation Programs. Completed HAER records are preserved in the HABS/HAER/HALS Collection at the Library of Congress, where the public can access drawings, photographs, written histories, and related documentation.
For project teams, HAER often becomes visible when an important engineering resource is being studied, altered, or demolished. But HAER isn't a designation, and a HAER record doesn't by itself mean a resource is listed in the National Register of Historic Places or that a project has been approved.
What does the Historic American Engineering Record document?
HAER focuses on engineering, technology, industry, and infrastructure. NPS lists subjects such as transportation systems, industrial buildings and machinery, public utilities, mines, bridges, watercraft, historic vehicles, and spacecraft.
The goal isn't simply to photograph something before it disappears. HAER documentation is intended to explain and illustrate what is significant or valuable about an engineering site, structure, or object, including how it was designed, built, operated, or changed over time.
Linn Cove Viaduct on the Blue Ridge Parkway is a useful example inside Preserve Signal's coverage area. NPS identifies the viaduct as HAER NC-42 and highlights its significance as an early U.S. example of precast segmental concrete bridge construction using the progressive placement method.
What does HAER documentation include?
A formal HAER record can combine several kinds of documentation. The exact package depends on the property's significance, complexity, available information, and the level of documentation required for the project.
- Measured or interpretive drawings that explain the structure, machinery, process, site, or engineering system.
- Large-format black-and-white archival photography prepared to Heritage Documentation Programs standards.
- Written historical and descriptive information explaining development, engineering significance, technology, use, alterations, and context.
- Existing drawings, field notes, or other supporting material when appropriate to the documentation scope.
For formal HABS/HAER/HALS photographs intended for the national collection, the Secretary's documentation standards call for large-format black-and-white safety-film negatives in 4x5, 5x7, or 8x10 format and one archival contact print per negative. The current NPS photography guidelines also specify use of a large-format view camera and archival processing.
For Section 106 mitigation, NPS commonly works with three documentation levels. Level I includes a full set of measured or interpretive drawings, photographs, and an outline-format historical report. Level II can use reproduced existing drawings with photographs and a historical report. Level III uses a sketch plan, photographs, and a short-format historical report. The appropriate level should match the nature and significance of the resource and the requirements established for the project.
HAER, HABS, and HALS are related but different
HAER is one of three National Park Service Heritage Documentation Programs. Preserve Signal's guide to the Historic American Landscapes Survey explains the landscape-focused program:
- HABS, the Historic American Buildings Survey, focuses primarily on historic architecture and buildings.
- HAER, the Historic American Engineering Record, focuses on engineering, industrial, technological, and infrastructure resources.
- HALS, the Historic American Landscapes Survey, documents significant historic landscapes.
The boundaries aren't based only on what a resource looks like. A large industrial complex, for example, may contain architecture, machinery, landscape systems, and engineering processes. The appropriate program depends on what the documentation needs to explain, and NPS can guide project teams when the fit isn't obvious. Preserve Signal's companion guide explains what Historic American Buildings Survey records can reveal.
HAER isn't the same thing as National Register listing
A resource doesn't have to be listed in, or even eligible for, the National Register to be included in the HABS/HAER/HALS Collection. NPS also says a property doesn't have to be at least 50 years old.
Likewise, creating a HAER record doesn't list or designate the resource. National Register eligibility is a separate evaluation based on significance, the applicable criteria, historic context, and integrity.
For that broader framework, see Preserve Signal's guide to the National Register of Historic Places.
How HAER fits into Section 106
HAER documentation is frequently used to resolve adverse effects under Section 106, especially when a historic engineering resource will be substantially altered or demolished. That doesn't mean Section 106 automatically requires HAER recordation.
When HABS, HAER, or HALS documentation is stipulated in a Section 106 Memorandum of Agreement or Programmatic Agreement, the agreement should define the required documentation. NPS recommends contacting the appropriate regional office early so the scope, documentation level, draft review, final formatting, and acceptance process are clear before fieldwork and production are complete.
HAER can also help federal agencies meet separate recording responsibilities under Section 110(b) of the National Historic Preservation Act when federal action or assistance will substantially alter or demolish a historic property.
For the underlying federal review process, see Preserve Signal's article on Section 106 and upcoming historic preservation work.
Who prepares and reviews HAER documentation?
HAER was created around an interdisciplinary approach to engineering and industrial history. Depending on the resource and scope, a project team may include historians, engineers, architects, photographers, industrial specialists, and other professionals.
For Section 106 mitigation projects, the NPS regional office serving the state coordinates review and acceptance for documentation intended for the national HABS/HAER/HALS collection. The Section 106 agreement or consultation process may also require review by the SHPO, THPO, federal agency, or other consulting parties. That project-specific compliance review is distinct from NPS technical review and acceptance under Heritage Documentation Programs standards. For donated projects outside Section 106 mitigation, Heritage Documentation Programs in Washington reviews submissions.
That review matters. A report described casually as 'HAER-style' isn't necessarily an accepted HAER record. Documentation intended for the national collection has to meet the Secretary of the Interior's Standards and the applicable Heritage Documentation Programs guidelines and transmittal requirements.
Some SHPOs also maintain separate state archival documentation standards for mitigation that doesn't warrant or require formal transmission to the Library of Congress. For example, Georgia uses Permanent Archival Record guidance for certain state- and local-level mitigation, while Maryland accepts HABS/HAER-standard materials into its own collections when they aren't forwarded to NPS. These state-level products can borrow from HABS/HAER methods, but they shouldn't be described as accepted HAER records unless they complete the NPS review and transmittal process.
Where do HAER records go?
Accepted HAER documentation becomes part of the HABS/HAER/HALS Collection at the Library of Congress. The Library of Congress is the designated repository for HABS/HAER/HALS documentation, although other repositories can keep duplicate copies.
The collection is public and searchable online. NPS reports that it now contains documentation for more than 46,000 sites across HABS, HAER, and HALS, including drawings, photographs, written histories, and field records.
That archive can be useful long after the original documentation project. Engineers, architects, preservationists, owners, researchers, and historians can use HAER records to understand former conditions, construction techniques, machinery, processes, alterations, and significant engineering features.
HAER is not a historic structure report
A HAER record and a Historic Structure Report can overlap in research and documentation, but they serve different purposes. An HSR is generally a planning and treatment document for the stewardship of a historic resource. HAER is archival documentation prepared to national standards for inclusion in the Library of Congress collection.
If you're comparing the two, see Preserve Signal's guide to the Historic Structure Report.
Why HAER can matter as a project signal
For firms tracking preservation work, HAER can be more than an archival acronym. A requirement for HAER documentation in a Section 106 agreement can indicate that an agency has identified an adverse effect and is defining mitigation before the affected resource is altered or demolished.
The documentation itself can also create professional-services work for historians, engineers, architects, photographers, and cultural resource firms. But a HAER requirement isn't proof that construction is imminent. Project design, permitting, funding, procurement, and the timing of the adverse action can continue on separate tracks.
For project-intelligence purposes, the signal is usually strongest when a HAER requirement aligns with design decisions, funding, permits, agency approvals, ownership activity, or procurement. That is the same approach described in Preserve Signal's guide to finding historic preservation projects before formal procurement.
The practical takeaway
The Historic American Engineering Record is the national program for documenting significant engineering and industrial resources through standardized historical, photographic, and graphic records.
If HAER appears in a project file, first ask why it's there. It may be an independent documentation effort, donated research, or a mitigation requirement tied to a federal undertaking. Then look for the documentation level, reviewing NPS office, agreement language, schedule, and the larger project that created the need for recordation.