The park has 29,182 acres of the scenic, northern most portion of the Palo Duro Canyon.  Palo Duro is spanish for "hard wood" in reference to the mesquite and juniper trees that are abundant in the area.  

The Canyon is 120 miles long, as much as 20 miles wide, and has a maximum depth of more than 800 feet. Its elevation at the rim is 3,500 feet above sea level. It is often claimed that Palo Duro Canyon is the second largest canyon in the United States, the largest being the Grand Canyon.

Palo Duro Canyon was formed by water erosion from the Prairie Dog Town Fork of the Red River. The water deepens the canyon by moving sediment downstream. Wind and water erosion gradually widen the canyon.

 
Rainbow over Palo Duro Canyon

Humans have resided in the canyon for approximately 12,000 years. Early settlers were nomadic tribes that hunted mammoth, giant bison, and other large game animals. Later, Apache Indians lived in the canyon, but were soon replaced by Comanche and Kiowa tribes who resided in the area until 1874. At that time, Col. Ranald Mackenzie was sent into the area to transport the Native Americans to Oklahoma. Col. Mackenzie and the 4th Cavalry were able to capture more than 1,400 horses belonging to the tribe. After keeping some of the best horses for themselves, the remainder were taken to nearby Tule Canyon and destroyed. Cut off from their only means of transportation, the Native Americans soon surrendered.

In 1876, Charles Goodnight entered the canyon and opened the JA Ranch. At its peak, the ranch supported more than 100,000 head of cattle. Goodnight operated the ranch until 1890. Although only a fraction of its original size, the JA Ranch remains a working ranch today.