The attraction began life as a proposal of a historical recreation of the Western Expansion of the United States, that would have been built on the banks of the Mississippi River in St. Louis, near the Jefferson National Memorial. Animator-Imagineer Marc Davis designed the attraction and characters in the form of drawings and models over a five-years period. Disney executives such as Richard Irvine and Roy Disney both liked the idea when presented with Davis' concepts. The attraction was to have been located inside, outside and around an architectural feature in Frontierland known as Thunder Mesa Mountain.