The National Park Service has found that 37 historic properties would be harmed by construction of a proposed 250-foot arch at Memorial Circle, the traffic circle below Arlington National Cemetery near the National Mall, according to NPR.

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

The findings came through a process known as a Section 106 review, required by the National Historic Preservation Act. That law obligates federal agencies to evaluate how their projects affect historic properties and to look for ways to reduce harm. The NPS produced two separate reports for this proposal: an Environmental Assessment, which examines broader environmental effects, and a Section 106 Assessment of Effects, which focuses on cultural and historic resources.

The two reports reached different conclusions. The Environmental Assessment found the project would not cause significant environmental impacts. The Section 106 assessment, however, determined that an arch at Memorial Circle would interfere with dozens of historic sites — especially the sightline between the Lincoln Memorial and Arlington House, the former home of Confederate Gen. Robert E. Lee.

The White House has defended the location. A White House statement called Memorial Circle an ideal site, describing the arch as a "fitting addition to the monumental axis between the Lincoln Memorial and Arlington House" and saying it would improve the visitor experience at Arlington National Cemetery. That statement addresses the same historic viewshed the NPS assessment identified as most at risk.

A group of Vietnam War veterans has sued to stop construction, arguing the arch would be a visual affront and requires congressional approval. The lawsuit adds a legal challenge on top of the ongoing regulatory review. Under the Section 106 process, federal agencies must consult with stakeholders and seek ways to avoid, minimize, or mitigate harm to historic properties.

Preservationists have pointed to the 37-property finding as evidence that the site deserves closer examination. They note that other locations in Washington could host an arch of this size with far fewer effects on historic properties. The NPS assessment does not evaluate alternative sites; its scope is limited to analyzing effects at Memorial Circle.

The split between the two reports reflects the fact that they operate under different laws. The Environmental Assessment follows the National Environmental Policy Act, or NEPA, which sets a broad environmental standard. The Section 106 process follows the National Historic Preservation Act, which focuses specifically on cultural resources. A project can pass the NEPA test 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 parties.

The viewshed between the Lincoln Memorial and Arlington House carries particular weight in preservation practice. That sightline was designed as part of the McMillan Plan, an early-20th-century effort to extend Pierre L'Enfant's original city plan, and it is one of the most protected views in the capital. Memorial Circle sits at the narrowest point of that axis, which is why the NPS assessment focused its adverse-effect finding there.

The 250th anniversary timeline adds pressure. Commemorations of the Semiquincentennial are already underway across federal agencies, and a signature monument intended for the anniversary would still 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.