The Dinosaur Diamond is a 486-mile (782 km) scenic and historic byway loop through the dinosaur fossil laden Uinta Basin of the U.S. states of Utah and Colorado. The byway comprises the following two National Scenic Byways: * The 328-mile (528 km) Dinosaur Diamond Prehistoric Highway in Carbon, Duchesne, Emery, and Grand counties, Utah; and * The 134-mile (216 km) Dinosaur Diamond National Scenic Byway in Garfield, Mesa, Moffat, and Rio Blanco counties, Colorado. The highway forms a diamond-shaped loop with vertices at Moab, Helper, Vernal and Grand Junction.