Theodore Roosevelt created Petrified Forest National Monument on December 8, 1906. Petrified Forest was designated as a national park on December 9, 1962.

The park has 93,533 acres (about 147 square miles) within park boundaries, with legislation in 2004 increasing the administrative boundary to 218,533 acres. Learn more about the Park Boundary Expansion.

The park has over 50,000 acres are designated Wilderness, spread out between the north and south ends of the park. Learn more about Wilderness on the Backpacking page.

Intermountain Basin semi-arid steppe and grassland (shortgrass prairie) constitute the main environment within the park.

Hundreds of species of plants and animals can be found in the park, including pronghorn, Gunnison's prairie dog, coyote, bobcat, bullsnake, Arizona tiger salamander, meadowlark, and golden eagle.

Over 10,000 years of human history can be found in the park, including over 800 archeological and historic sites.

Puerco Pueblo was built by the ancestral Puebloan people, occupied between A.D. 1200 and 1400. Agate House was occupied about A.D. 1100-1150 and was built out of pieces of petrified wood.

Herbert David Lore built Painted Desert Inn by 1924. Using designs by National Park Service architect Lyle Bennett, the Civilian Conservation Corps (CCC) reconstructed the Painted Desert Inn in the late 1930s. From 2004-2006 the building had an extensive rehabilitation, returning the inn to its 1949 appearance.

Petrified Forest National Park is the only national park site that contains a segment of the Historic Route 66 alignment. Part of the National Old Trails Highway also passed through the park.

The Chinle Formation of the Triassic Period (about 225 million years ago) is the main geologic formation of the park. The Bidahochi Formation outcrops in the north, laid down during the Miocene and Pliocene of the Quaternary Period, about 3-8 million years ago.

The brilliant colors in the petrified wood come mainly from three minerals. Pure quartz is white, manganese oxides form blue, purple, black, and brown, and iron oxides provide hues from yellow through red to brown.

Annual visitation to the park is about 600,000 people. You can visit the Public Use Statistics Office website for all park visitation statistics.

Each year, tons of petrified wood are removed illegally from the park, even though it can be purchased legally from rock shops nearby. The rock shops sell petrified wood collected from private land outside the park boundaries.