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.