A hint of sunlight on a cloudy afternoon illuminates the limestone cliffs that form the Santa Elena Canyon in Big Bend National Park. This classic viewpoint is directly off the Ross Maxwell Scenic Drive and has panoramic views of the canyon cutting right through sheer cliffs that rise 1500 feet above the Rio Grande. These enormous cliffs mark the boundary between the United States and Mexico. The left side of the canyon is in Mexico and the right side of the canyon, which includes the Santa Elena Trail, is in Texas.