"On June 9-10, 1972, extremely heavy rains over the eastern Black Hills of South Dakota produced record floods on Rapid Creek and other streams in the area. Nearly 15 inches of rain fell in about 6 hours near Nemo, and more than 10 inches of rain fell over an area of 60 square miles (Schwartz and others, 1975). According to the Red Cross, the resulting floods left 238 people dead and 3,057 people injured. In addition to the human tragedy, total damage was estimated in excess of $160 million (about $664 million in 2002 dollars), which included 1,335 homes and 5,000 automobiles that were destroyed (Schwartz and others, 1975) (fig. 1)."
U.S. Geological Survey: http://www.usgs.gov/