See the context of this sign.

The Power to Carve a Mountain

Over 450,000 tons of rock were
removed from Mount Rushmore to
bring out the four presidentional faces.
Although about 90% of the rock was
removed with dynamite, the
remaining rock was removed by drilling
with jackhammers and wedging the
rock off the mountain. The final
finishing work on the faces was
completed using small jackhammers
and facing bits. Air compressors
located here at the base of the mountain
provided the power to operate these

The Ingersoll-Rand Imperial Type to Air
Compressor displayed here was the
largest of three in operation in the
compressor house which stood at this
location during the carving work. For
much of the life of the carving, Keystone
Consolicated Mines provided the electrical
power to operate these compressors.

An 1,800-foot, 3-inch pipeline followed the
stairway up the mountain to carry air for
the jackhammers from the compressors
below. In cold weather, a liquid gas was
injected in a fine mist into the pipeline
beyond the compressors to prevent
freezing. The pipeline was later enlarged
and expanded to provide compressed air
to more jackhammers.

In 1936, Julian Spotts, a National Park Service
engineer, checked this system for leaks. He
discovered the blacksmith had tapped into the
line with a nozzle to blow compressed air on
himself while he worked! Spotts provided a fan

Spotts also tried to discover the reason for a large
power loss suffered at Rushmore every Monday
morning. "Well, I found," said Spotts, "that just
about every woman in Keystone washed clothes
on Monday, and a lot of them had electric
washing machines." Instead of trying to rearrange
Keystone's laundry schedule, Spotts asked the
Mount Rushmore Commission to buy a
gasoline-powered auxiliary compressor. "And
after that," according to Spotts, "we had no
more power problems." These improvements
increased the minimum number of jackhammers
that could be operated from 16 to 32.

Black Hills Power and Light completed a
powerline to Rushmore in 1939. This provided
all the electricity needed for the remaining two
years of carving work. Today, this compressor
and sections of pipe still in place on Mount
Rushmore stand as a testimony to the power it
took to carve a mountain.

Don't miss the rest of our virtual tour of Mount Rushmore in 585 images.