Big Bend National Park is a national park located in Texas, USA. For more than 1,000 miles (1600 km), the Rio Grande / Río Bravo forms the international boundary between Mexico and the United States, and Big Bend National Park administers approximately 245 miles along that boundary.

Big Bend National Park has national significance as the largest protected area of Chihuahuan Desert topography and ecology in the United States. The park covers 1252 mi² (3242 km²). Few areas exceed the park's value for the protection and study of geologic and paleontologic resources. Cretaceous and Tertiary fossil organisms exist in variety and abundance. Archeologists have discovered artifacts estimated to be 9,000 years old, and historic buildings and landscapes offer graphic illustration of life along the international border in the 1800s.

Because the Rio Grande serves as an international boundary, the park faces unusual constraints when administering and enforcing park rules, regulations, and policies. In accordance with the Treaty of Guadalupe Hidalgo, the park has jurisdiction only to the center of the deepest river channel as the river flowed in 1848. The rest of the land south of that channel, and the river, lies within Mexican territory.
 

Big Bend National Park, Texas - Official Site