This legislation, known as the Gateway Arch National Park Boundary Revision Act of 2026, aims to modify the official boundary of Gateway Arch National Park. It specifically amends the Act of May 17, 1954, which originally established the park's parameters. The bill's primary provisions include an adjustment to the park's authorized size, increasing it from 100 acres to 102.18 acres . Furthermore, it updates the official reference map for the park's boundary. The outdated map from January 1992 is replaced with a new map titled "Gateway Arch National Park Proposed Boundary Revision," numbered 366/189,627, and dated August 2023, ensuring accurate representation of the park's current extent.