As the old "Mine Train Thru Nature’s Wonderland" attraction was getting older, it was decided to replace it and make way for the new Disneyland Master Plan and Discovery Bay. So the old Mine Train was closed in favor of building an attraction would would be the focal point of expansion. A new thrill ride called the "Big Thunder Mountain Railroad".

Nine models based on Baxter’s new Bryce Canyon motif were built at 1/20 inch scale to simulate track layouts and designs. Once the designs were finalized a ½ to 1-inch scale model was created that demonstrated the layout of Big Thunder over the proposed three acre site. On a grid plotted backstage at Disneyland, Imagineers began the process of enlarging the model into the full size mountain. Using the model as reference they bent iron rebar into the shapes and contours of the mountain The iron rebar was later covered with steel mesh and would finally be covered with concrete and textured to fit the model.

Show elements were built at MAPO and shipped to Disneyland. These included the goats, coyotes, opossums, bats, and mineral pools. WED Imagineers scoured the desert of the west to acquire the authentic mining equipment placed all throughout the attraction. 230 tons of actual gold ore was trucked in from the Mojave Desert.

Finally in September of 1979, Big Thunder Mountain Railroad opened to the public at Disneyland. Since then the attraction has been reproduced at all four of the Magic Kingdom Parks all over the globe and has been enjoyed by millions.