The Mount Rushmore National Memorial is in the Black Hills near Keystone, South Dakota. [Photo/Agencies]

Along the way, it has also found a place in pop culture. A chase scene in North by Northwest, Alfred Hitchcock's 1959 classic starring Cary Grant and Eva Marie Saint, included a death-defying scramble over the presidents' faces.

"Alfred Hitchcock says he expects to realize his long ambition－filming a chase over the Mt. Rushmore Monument," The Associated Press reported in 1958. "He may be spoofing, but you never can tell with Hitchcock." Some scenes were filmed at the memorial, but the climbing of the faces were studio shots that used models of the mountain.

A 1983 special anniversary issue of the comic Wonder Woman features her face next to the stone Lincoln. T-shirts with the faces of superheroes instead of the presidents are available at Target and elsewhere. The memorial is a muse for political cartoonists.

The memorial has also been featured in multiple coins, including a quarter issued by the US Mint in 2013 that shows men adding the finishing details to Jefferson's face. The four faces have also been highlighted in postage stamps, and they are－of course－in the background of South Dakota's license plates.

To celebrate the milestone, the National Park Service held events during the summer in connection with its own 100th birthday.

The memorial should be lauded for several reasons, according to Debbie Ketel Speas, communications director for the nonprofit Mount Rushmore Society, especially its impact on the state's tourism industry and economic development, as well as the efforts of those who worked to make it a reality.

"When you look at what they achieved over 75 years ago, it's quite spectacular," she says.