The National Park Service has released findings identifying 37 historic properties that would be adversely affected by construction of a proposed 250-foot arch at Memorial Circle, the traffic roundabout below Arlington National Cemetery near the National Mall, according to NPR.

President Trump proposed the arch, formally designated the United States Triumphal Arch, to serve as a signature monumental structure honoring the nation's 250th anniversary. The NPS is developing the design and has listed the project among George Washington Memorial Parkway projects on its ParkPlanning website. The structure, if built, would alter views across Washington and Arlington Cemetery, as The New York Times reported on August 3.

The NPS findings were issued as part of a Section 106 review under the National Historic Preservation Act, which requires federal agencies to evaluate impacts on historic properties and attempt to minimize harm. The agency's Section 106 Assessment of Effects report, along with an Environmental Assessment, forms the regulatory record for the proposal. The Environmental Assessment concluded the project would not result in significant environmental impacts. The Section 106 assessment, however, reached a different conclusion on cultural resources: an arch in Memorial Circle would interfere with dozens of historic sites, particularly the visual and spatial connection between the Lincoln Memorial and Arlington House, the former home of Confederate Gen. Robert E. Lee.

The White House has defended the selected site. Memorial Circle is an ideal location, a White House statement said, calling the arch a "fitting addition to the monumental axis between the Lincoln Memorial and Arlington House" and saying it would enhance the visitor experience at Arlington National Cemetery. The statement directly engages the same historic viewshed that the NPS assessment identified as most at risk.

A group of Vietnam War veterans has sued to halt construction, arguing the arch would be a visual affront and requires congressional approval. The lawsuit adds a legal track to the regulatory process already underway through the Section 106 framework, which obligates federal agencies to consult with stakeholders and seek ways to avoid, minimize, or mitigate adverse effects on historic properties.

Preservationists have pointed to the 37-property finding as evidence that the site selection deserves scrutiny, noting that other locations in Washington could accommodate an arch of this scale with far fewer adverse effects on historic properties. The NPS assessment does not evaluate alternative sites; its scope is limited to analyzing effects at Memorial Circle specifically.

The interplay between the Environmental Assessment's finding of no significant environmental impact and the Section 106 assessment's identification of 37 adversely affected historic properties creates a layered regulatory picture. The two reviews operate under different statutory standards: the National Environmental Policy Act governs the EA, while the National Historic Preservation Act drives the Section 106 process. A project can clear the NEPA threshold while still triggering obligations under Section 106 to resolve adverse effects through consultation with the Advisory Council on Historic Preservation, state historic preservation officers, and other consulting parties.

The viewshed between the Lincoln Memorial and Arlington House carries particular weight in historic preservation practice. That axis, designed as part of the McMillan Plan's extension of the L'Enfant city, is one of the most protected sightlines in the capital. An intervention at Memorial Circle sits at the geographic pinch point of that axis, which is why the NPS assessment focused its adverse-effect finding there.

The 250th anniversary timeline adds pressure. Semiquincentennial commemorations are already underway across federal agencies, and a signature monument intended for the anniversary would need to navigate the Section 106 consultation process, the veterans' lawsuit, and any congressional authorization questions the litigation raises. The NPS has not announced a construction timeline.