Next month, Arizona residents will be asked to decide whether the Grand Canyon belongs to all Americans, or only to Arizonans. The controversial ballot measure put forth by Republicans in the state legislature is intended to wrest control of millions of acres of federal land, including Grand Canyon National Park. Proposition 120 asserts Arizona's right to complete control over "air, water, public lands, minerals, wildlife and other natural resources within the state's boundaries." The Sierra Club estimates that the area of land in contention constitutes between 39,000 and 46,700 square miles, or about 40 percent of the entire state. Conservation organizations, such as the Arizona Wilderness Coalition, have come out against the proposition, claiming that the transfer of federal property to state control would result in mismanagement and massive sales of public land.