Mount Rushmore

Most of the rock was blasted away with dynamite.

Then workers in swings hung from cables. They drilled lots of little holes, chipped off the rock and made the faces smooth.

Borglum made models of the faces, where one inch on the model equaled one foot on the mountain. Workers used measuring tools on the model and the mountain to know how much rock to remove, and where.

About 90% of the carving was done with dynamite. Powdermen set charges to blast away exact amounts of rock, stopping about 3 to 6 inches from the final surface. Then drillers, hanging in seats called bosun chairs on steel cables, drilled holes close together, a step called honeycombing. The rock between was chipped off, and a tool called a bumper smoothed the granite. Even with all this danger, no one died during the 14 years of work.

Borglum studied life masks, paintings, photographs and descriptions of the four presidents and built plaster models at 1:12 scale. Using a 'pointing system', with one measuring device on the model and another on the mountain, workers calculated where and how much rock to remove.

Roughly 90% of the stone was removed with dynamite; skilled blasters could work within a few inches of the planned surface, leaving 3 to 6 in. Workers then climbed some 700 stairs each day and were lowered over the 500 ft face in bosun chairs on 3/8-inch steel cables, cranked by winches and guided by call boys relaying messages. Pneumatic drills honeycombed the remaining granite with closely spaced holes; the excess was chipped away and the surface 'bumped' smooth. The NPS records no fatalities in 14 years of construction among nearly 400 workers, many glad of a job during the Depression.

About two million people visit Mount Rushmore every year.

Park workers climb down the faces on ropes. They fill cracks so water and ice cannot break the rock.

About two million visitors come to Mount Rushmore each year. To protect the sculpture, National Park Service staff rappel down over the faces to look for cracks. They seal them with a silicone sealant so water and ice cannot get in and split the rock. The granite wears away very slowly, about one inch every 10,000 years.

The Black Hills were home to Native American peoples long before the carving. The Lakota call the hills Paha Sapa, and many tribes still see the whole area as an important place.

The NPS counts around two million visitors a year. Staff rappel over the faces to inspect and caulk cracks with silicone sealant, keeping out moisture so that freezing water cannot split the stone; erosion is estimated at about one inch every 10,000 years.

The NPS also records an older history. People lived in the Black Hills by about 7000 BCE, and the Lakota controlled the region by the late 1700s, calling it Paha Sapa. The 1868 Treaty of Fort Laramie recognized the Black Hills as Lakota territory, but after gold was found in 1874, prospectors and settlers occupied the area in violation of the treaty, and by the end of the 1800s many Lakota had been forced onto reservations. The treaty had said that no land could be given up unless three-fourths of the adult Sioux men signed; the agreement behind Congress's act of 1877, which took the Black Hills, was signed by about 10%. In 1980, in United States v. Sioux Nation of Indians, the US Supreme Court ruled that the 1877 act was a taking of Sioux land that required just compensation. The NPS notes that the whole range holds cultural and spiritual value for several tribes, many of which regard it as a Traditional Cultural Place.