The Colorado River is one of the most significant rivers in the southwestern United States. It stretches through seven states and is an essential source of water and power for millions of people. It is also home to numerous rare and endangered species of plants and animals. Synonyms for the Colorado River include "the Grand River," "the Great River," "the Red River," and "the Mighty Colorado." Its name derives from the reddish-brown silt that it carries along its length. The river is renowned for its spectacular canyon formations, including the Grand Canyon, which is one of the country's most popular tourist destinations.