Nine Mile Canyon is a canyon, approximately 40 miles (60 km) long, located in the counties of Carbon and Duchesne in eastern Utah, in the Western United States. Promoted as “the world’s longest art gallery”, the canyon is known for its extensive rock art, most of it created by the Fremont culture and the Ute people. The rock art, shelters, and granaries left behind by the Fremont make Nine Mile Canyon a destination for archaeologists and tourists alike.

The canyon became a main transport corridor in the region during the 1880s. Settlers established a number of ranches in Nine Mile, and even a short-lived town named Harper. No longer heavily traveled, the rugged canyon road was used mostly for recreation and tourism through the end of the 20th century. The discovery of rich deposits of natural gas deep beneath the Tavaputs Plateau has brought an influx of industrial truck traffic since 2002. The large amounts of fugitive dust produced by the trucks’ passage may be damaging the rock art. Public debate is ongoing about how best to balance energy development in the canyon against the preservation of its cultural resources.