Ruby Canyon, Protected area in Utah, United States.

Ruby Canyon is a roughly 25-mile (40 km) canyon on the Colorado River along the Colorado–Utah border. Its walls are lined with ruby-red sandstone cliffs, and the river cuts between tall, reddish-orange formations streaked with dark brown and black. The canyon is a protected area and a rafting destination with overnight camping by permit.

The canyon was crossed by the Denver and Rio Grande Western Railroad in the early 1900s, which created an important connection between Colorado and Utah. This railroad route shaped the region's development significantly.

The name Ruby Canyon comes from the ruby-red sandstone cliffs along the Colorado River. Near the Utaline Siding, the words "Utah | Colorado" are painted on the canyon wall at the state border, a landmark noted by train travellers.

The area is popular for rafting and hiking, with limited overnight options and visitors should come well prepared. The best time to visit is during warmer months when water levels are more favorable.

The canyon's name comes from the ruby-red sandstone of its walls, and the only land access is the Union Pacific line between Mack, Colorado, and Westwater, Utah. Amtrak's California Zephyr uses this track between Grand Junction and Thompson Springs, passing the painted words "Utah | Colorado" on the canyon wall at the state line beside Utaline Siding.