The idea of Mount Rushmore began in 1923. Doane (rhymes with "bone") Robinson, state historian of South Dakota, wanted to promote tourism in the Black Hills. He floated the idea to Gutzon Borglum. Borglum was unexpectedly available owing to his untimely departure from the Stone Mountain project he'd begun in Georgia. He jumped at the chance to produce a monument dedicated to the history of the United States (and possibly just to have a job). By 1925, they had secured federal funding for the project.
Why here? Three reasons. First, this mountain is composed of fine-grain granite. Second, it towers above much of its surroundings. Third, this cliff faces southeast. It's the best light for viewing and photography. (Yes, that was a big consideration, even in the 1920s.)
Carving commenced on October 4, 1927. Fourteen years and countless funding challenges later, it was officially finished on October 31, 1941. The project cost just under $1 million and employed about 400 workers. Remarkably, none died while working on the project.
What you see on Mount Rushmore today is only a small portion of what its sculptor originally envisioned. Gutzon Borglum wanted to carve the presidents' whole torsos (head to waist, as shown in this model in the "Sculptor's Studio"). He also wanted a feature called "The Entablature", an enormous tablet engraved beside the carvings of the four presidents. It would tell the story of the first 150 years of U.S. history. President Coolidge was originally given the honor of writing the essay. But then he died in 1933. So, the next year they held a public contest. Thousands of people submitted essays. Alas, the Entablature had to be scrapped when Jefferson had to be moved to Washington's other side, and they needed room for Lincoln.
When his dream of the Entablature was dashed, Gutzon Borglum developed a new plan. He would build a "Hall of Records" behind the sculpted heads. The 80 by 100 foot chamber would display the winning history essay, plus hold any other important documents and artifacts the government wanted to preserve there. The room would be reached via an 800-foot granite staircase. Regrettably, the new plan, too, had to be abandoned. They had only managed to blast out a 70-foot tunnel when, in 1939, Congress directed all efforts toward finishing the faces. In 1998, a small vault was laid inside the tunnel. The winning essay, as well as a few other engravings and documents, were sealed inside for eternity.
The faces could conceivably outlast the human race. The granite will only erode a tenth of an inch in a thousand years. (By comparison, the Sharps layer of the Badlands erodes 10,000 times faster, at the rate of one inch per year). Still, there's some maintenance to be done. For example, any crack is subject to frost-wedging, so it gets sealed with silicone caulk. The faces are also infrequently pressure-washed to remove lichens.
The four faces stare back through the window to the left of the model in the Sculptor's Studio. See Washington's face on the far right?
The heads on the mountain are about 60 feet tall.
Outside the park, there's a pulloff where you can see Washington's head protruding from the mountain.