Project Blue Book Case #4841. On July 27, 1957, witnesses in Longmont, Colorado — a community on the Front Range approximately 35 miles north of Denver — observed a bright object in the sky. Longmont sits at the edge of the Great Plains where the Rocky Mountain foothills rise to the west, providing dramatic terrain and clear mountain air.
Colorado's Front Range corridor was one of America's most militarily significant landscapes. Lowry AFB in Denver, the Air Force Academy in Colorado Springs, NORAD at Cheyenne Mountain, and various missile test facilities were all within 100 miles. The corridor's airspace was heavily used by military aviation.
July 1957 preceded the dramatic Sputnik-triggered wave by just three months. The case was classified "Unknown."