I’ve been to a Petrified Forest, north of Napa, before; but the Petrified Forest in Arizona is far more massive in size and more ancient. Parts of the 7,500 square foot Painted Desert is hundreds of millions of years up to a billion years old.
The surface of the painted forest existed when the supercontinent Pangea existed, during the age of the dinosaurs. Therefore, several teams of archeologists have come in search of dinosaur remains.
In prehistoric times, the Painted Desert served as a trade route for various Native American peoples.
In 1906, Theodore Roosevelt signed an act making the Painted Desert the United States of American’s second national monument. In total, during Theodore Roosevelt’s presidency, he signed into law the creation of 5 National Parks and 18 National Monuments.
In the 1920s Route 66 was built inside the boundaries of the Painted Desert. Soon after the creation of the highway the Painted Desert Inn and The Lion Farm were created as roadside attractions.
An abandoned vehicle marks a portion of the Route 66 that lay within the Painted Desert.
More Information on the creation of National Parks in the United States can be found in this National Geographic article.