The Black Hills Flood of 1972 caused 238 deaths and 3,057 injuries. Several bodies were never found. Over 1,335 homes and 5,000 automobiles were destroyed. The value of the damaged property was over US $160 million in 1972 dollars.
15" inches of rain in 6 hours.

Cloud seeding experiments by the federal government were being conducted just west of Rapid City two days before the torrential downpour. The Feds acknowledged they were cloud seeding just prior to the event but denied it had anything to do with it.

Move on nothing to see here they said. Evil *******s then and now.

Rapid City flood video at https://vimeo.com/28328166