What is Section 106 Review?

Section 106 is part of the National Historic Preservation Act (NHPA), which was enacted in 1966. Established in the wake of urban renewal programs that demolished many historic properties throughout the United States, the NHPA created multiple programs and agencies to provide for the recognition and preservation of the country’s historic buildings, sites, and structures on a federal level. These include the National Register of Historic Places, State Historic Preservation Offices, and Section 106. Section 106 mandates that projects carried out or funded by federal agencies must take into account those projects’ potential impacts on historic properties. The Section 106 review process ensures that negative effects to historic properties are avoided, minimized, or mitigated.

For Section 106 purposes, “historic” is defined as properties that are listed or eligible for listing in the National Register of Historic Places. The first step in the Section 106 review process is to determine if the project might affect a historic property. To do so, an Area of Potential Effects (APE) is established. If the project involves work done on a single building, the APE might be limited to that building’s footprint, but if the project is the construction of a large wind farm, the APE might encompass all properties from which the wind farm would be visible. At this stage, a historic resources survey might be done in order to find and document all potentially affected properties.

If it is determined that historic properties will be affected by the project, the federal agency must notify all interested parties. This may include the State or Tribal Historic Preservation Office, the local municipality, and state or local preservation organizations. The next step is determining whether the effects on the historic property are adverse. Adverse effects may be as clear-cut as the planned demolition of a historic building, but can also include fundamental changes to a historic property’s setting, e.g. planned construction of a housing development immediately adjacent to a historic farm, or significant changes to a historic building, such as the construction of a large addition.

If the effects are determined to be adverse, the agency and consulting parties must work together to come to an agreement about what will be done to avoid or mitigate the effects. A project may be relocated to a different site or reconfigured to no longer be in view of a historic property; proposed alterations to a historic building may be redesigned in order to be less obtrusive. In cases where changes to the project are not feasible, though, mitigation is pursued instead. Mitigation either minimizes the negative effects as much as possible or attempts to offset them in some way. A housing development might still be built next to a historic farm, but will be screened with trees. A large-scale addition might still be made to a historic library, but the agency will also provide funding to restore the library’s original façade. A historic building might be demolished, but is thoroughly documented beforehand, its materials salvaged for reuse, and signage about its history installed at the former site.

By mandating a review of potential effects to historic properties, the Section 106 process provides a layer of protection to these properties, ensuring that they are taken into account when federal projects are carried out.

Tabitha O’Connell - 2026