The Colorado River Basin lies in the southwestern United States. By geography and by the law of the river, the Colorado River Compact of 1922, the basin is divided into the mountainous upper basin, Colorado, New Mexico, Utah and Wyoming, where most of the runoff in the basin originates and the dry lower basin, Arizona, California, and Nevada, where there is great demand for the water in the river. A United States Supreme Court decision, usually termed the "Consolidated Decree", the Consolidated Decree entered by the United States Supreme Court in the case of Arizona v. California, 547 U.S. 150 (2006), also applies. The United States has a delivery obligation to the United Mexican States (Mexico) for certain waters of the Colorado River pursuant to the February 3, 1944 Treaty between the Un