Earlier this year, the National Park Service turned 100 and on Halloween, Mount Rushmore National Memorial turns 75. The mountain’s carved sculptures of presidents George Washington, Thomas Jefferson, Abraham Lincoln, and Theodore Roosevelt attract nearly 3 million visitors every year. In celebration of Mount Rushmore’s 75th birthday, here are a few facts about South Dakota’s biggest tourist attraction.

Why was it made?

In the early 1920s, area historians were brainstorming ideas to attract visitors to South Dakota. One suggested sculpting figures of historic people from the West out of natural granite pillars. Sculptor Gutzon Borglum suggested that four presidents whose legacies involved important events in U.S. history would draw more national attention. Borglum was right—it’s now known as the “Shrine of Democracy” and is one of the country’s most popular tourist destinations.

How was it carved?

It took 400 men more than a decade to build Mount Rushmore. Many of them were miners who came to the Black Hills of South Dakota in search of gold. When their searches failed, they found work for $8 per day constructing and carving the mountain. Luckily, no artistic skills were required because 90 percent of the mountain was carved using dynamite and jackhammers. The men helped to remove nearly 450,000 tons of rock. The resulting faces of Mount Rushmore stand 60 feet tall; Washington’s nose is 21 feet long. The project took 14 years to complete, but would have taken longer if funding hadn’t run out. Initially, Borglum wanted the carvings to represent the presidents from the waist up but was forced to stop at only their heads.

Why these four presidents?

Borglum believed that each president selected should represent historically significant events in U.S. history, which is why he chose Washington, Jefferson, Lincoln, and Roosevelt. When the monument was four years away from completion, Congress introduced a bill proposing that women’s rights advocate Susan B. Anthony be included in Mount Rushmore. Unfortunately, it was dismissed because funding was only approved for the carvings that had already been started.

If you’d like to take part in celebrating the anniversary of Mount Rushmore, on October 22, the Black Hills Symphony, Dakota Choral Union, and the Black Hills State University Chorus will be performing at Rushmore Plaza Civic Center.

>>>Next: 10 Crowd-Free National Parks You Should Visit Instead