Canyonlands National Park is located in southeastern Utah with the confluence of the Green and Colorado rivers located near the center of the park. The area had been promoted during the 1930s for inclusion into the park system as part of a much larger Escalante National Monument. However, that effort did not succeed, and in 1961 Utah Senator Frank Moss introduced legislation in the United States Senate calling for the establishment of Canyonlands National Park. After considerable opposition within the state, the legislation was passed and on 12 September 1964 President Lyndon Johnson signed the act making Canyonlands the thirty-second national park. The park is the largest of Utah's five national parks, with a total of 337,258 acres. It is known for its rivers, canyons, mesas, pillars, standing rocks, grabens, and arches. All the rocks in Canyonlands are sedimentary.