Originally established in 1915 by President Wilson, the monument encompassed only 80 acres to preserve a rich assemblage of fossilized skeletal remains.  Twenty-three years later in 1938, the monument was enlarged to include the deep canyons of the Green and Yampa rivers, a total of 200,000 acres.  

The area was first explored by General William H. Ashley in 1823; then Major John Wesley Powell in 1869 and 1871.  Dinosaur bones were first noted in the area as early as 1882, but the great concentration of bones that the monument is known for was found by Earl Douglas in 1909.

Between 1909 and 1922, the Carnegie Museum conducted a major excavation of over 700,000 pounds of bones that they shipped back east to study.  Fossils found in the Morrison Formation (Jurassic) at the monument are fresh-water mussels, tortoises, Hoplosuchus (a small thecodont reptile), Camptosaurus, Apatosaurus, Allosaurus, and Diplodocus.

The monument is located on the east end of Uinta Mountains, near the confluence of Green and Yampa rivers.  The Uinta Mountains represent an east-west trending anticline; the only east-west trending mountains in Colorado.  The core of these mountains contains thousands of feet of very lightly metamorphosed rocks, one of the most noted, the Red Creek Quartzite represents the oldest rocks in Colorado, 2.3 billion years old.

Economically, the area has capitalized on the dinosaur remains, primarily the town of Dinosaur, originally Artesia.  The Rangely Oil Field, discovered in 1933 and developed since 1948, has produced over 800 million barrels of oil from the Mancos Shale and Weber Sandstone.  Also the Deserado Coal Company, located north of Rangely, produces coal from the Mesaverde Group.