As the Rio Grande flows from the mountains of Colorado to the Gulf of Mexico, it’s a natural border, a unique ecosystem, and a lifeline for wildlife and people alike. It runs through wetlands, forests, deserts, and floodplains, providing water for agriculture, and a home for numerous birds, plants, and animals, including half of all butterfly species in North America. In order to preserve delicate habitats and their residents, Laguna Atascosa and Santa Ana National Wildlife Refuges were established in the 1940s. The Lower Rio Grande Valley National Wildlife Refuge was created later to connect pockets of land along 275 miles of the river.