Palo Duro 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 Palo Duro State Park entrance is about 30 miles south-east of Amarillo, TX.