The Boquillas Crossing Port of Entry in Big Bend National Park, Texas, is a unique crossing on the 1,954-mile U.S.-Mexico border. Despite President Donald Trump's plans to build a border wall through Big Bend, which threatened to cut off this port from the river and the Mexican village of Boquilla del Carmen, where 200 residents depend on American tourism. The port only opens on Fridays and Mondays, forcing tourists to leave Mexico before sundown. The 1848 Treaty of Guadalupe Hidalgo established the Rio Grande as the boundary between Texas and Mexico, giving it a fluid border that would float as the river flooded, narrowed or shifted course. Despite significant lobbying from both sides of the border, the Obama administration and Mexico reached an agreement in 2010 to reopen this crossing. The larger idea of connecting visitors to preserve lands with both nations still persists.