Mule Pack Frontierland attraction at Disneyland; from July 17, 1955, to February 1, 1956. Became Rainbow Ridge Pack Mules (1956-1959) and Pack Mules Through Nature’s Wonderland (1960-1973). Walt Disney insisted that mules be a part of his Frontierland, even though they were ornery animals that would often nip the guests or refuse to move. Disney felt that they helped give the necessary ambience to the western theme. As new attractions were added to Frontierland, there was more to view while riding the mules.