The GILA River is a 649-mile long tributary of the Colorado River located in the U.S. states of Arizona and New Mexico. It is the sixth-longest river in the American Southwest and provides an important source of water for the region. The GILA River is also home to a variety of wildlife, including fish, amphibians, reptiles, birds, and mammals. The GILA River is an important part of the cultural heritage of the region, with many Native American tribes having lived along its banks for centuries.