The national park in the Southwest United States known for its sandstone formations is Arches National Park.

Arches National Park, located in eastern Utah, is renowned for its over 2,000 natural sandstone arches, including the iconic Delicate Arch. The park’s unique geological formations, such as fins, pinnacles, and balanced rocks, were shaped by millions of years of erosion and weathering. Visitors are captivated by the vibrant red rock landscapes that seem to glow under the sun. Popular activities in the park include hiking, photography, and stargazing, as it is also a designated International Dark Sky Park. This stunning destination exemplifies the dramatic beauty of the Southwest's desert environment.