Mt. Rushmore is very close to Sturgis, South Dakota. During the time I rode through the area the Famous motorcycle rally was in full swing in Sturgis. The event is so large it attracts around 600,000 bikers. I didn't really stop, I just kept riding. Mt. Rushmore was pretty neat. Iunfortunatly didn't make it to Crazy Horse.
http://en.wikipedia.org/wiki/Mt._Rushmore
http://en.wikipedia.org/wiki/Construction_of_Mount_Rushmore
http://en.wikipedia.org/wiki/Crazy_Horse_Memorial