DATE: June 1972
LOCATION: South Dakota
DEATHS: 238, with more than 3,000 injured
ESTIMATED COST: $826 million *
WHAT HAPPENED: Rains over the Black Hills produced record floods on Rapid Creek and other area streams. Heavy debris in the floodwaters clogged the spillway of the Canyon Lake Dam, which failed, sending a flood wave into Rapid City. Much of the damage occurred because people were living in the floodway. After the event, housing was relocated, but many businesses were allowed to remain.
*All costs estimated in 2009 dollars.
