See the context of this sign.

A monument's dimensions should be determined
by the importance to civilization of the events
commemorated... Let us place there, carved high,
as close to heaven as we cann,... our leaders,
their faces, to show posterity what manner of
men they were. Then breathe a prayer that these
records will endure until the wind and the rain alone
shall wear them away. - Gutzon Borglum - 1930

The Union of these four presidents carved on
the vace of the everlasting hills of South Dakota
will constitute a distinctly National Monument.
It will be decidedly American in its conception, in
its magnitude, in its meaning and altogether worthy
of our country. - From Dedication
Address by President Calvin Coolidge - 1927

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