An early start for the hour long drive back to queue for Wind Cave tour tickets and managed to secure some for 8.40am. Largest number of boxwork formations found in a cave. After breakfast by a field of prairie dogs set off on the 45 min wildlife loop road of the Custer State Park - lovely rolling hills but strangely devoid of wildlife apart from a small herd of Bison and 3 pronghorns. Stopped by a lake to sit out a storm. Read there was potential of golf ball sized hail and didn't want to write off another vehicle in this way so scarpered to the nearest petrol station. A car drove in later with hail damage. Next stop was Mount Rushmore ($5 for oap). very impressive. Learnt about how it was carved (17 years) and the unfulfilled plans for inscriptions and a national vault .