Big Bend National Park in west Texas covers 801,163 acres, which is larger than the state of Rhode Island. For more than 1,000 miles (1,600 km), the Rio Grande/Río Bravo river forms the international boundary between Mexico and the United States, and Big Bend National Park administers approximately 118 miles (190 km) along that boundary. The park was named after the area, which is bounded by a large bend in the river and Texas-Mexico border.
We have more photos of mammatus clouds here: Ten amazing photos of mammatus clouds