June 20, 1957
This is a video of the devastating tornado that hit Fargo, North Dakota. From Wikipedia:
The Fargo tornado of 1957 was a violent and deadly tornado that struck Fargo, North Dakota on June 20, 1957. The tornado struck the north Fargo (Golden Ridge) area in the early evening hours, causing major devastation. Well over 1,0 homes were either destroyed or damaged beyond repair and some of them were completely swept off their foundations - a classic example of F5 damage. 13 people were killed. After 1971, when Dr. Ted Fujita introduced his scale that rates tornadoes based on the damage they cause, the Fargo tornado received an F5 rating, the most severe level. The tornado's track was short, travelling only 9 miles (15 km), but the twister itself was fairly large, about 700 feet wide. This tornado was part of a family of tornadoes which was spawned by a supercell thunderstorm that moved through most of North Dakota and into parts of Minnesota.
Debris from the tornado was found as far as western Minnesota, over 50 miles east of Fargo in Becker County.
This tornado is considered the most devastating in North Dakota history, and was one of only two F5 tornadoes that have struck the state, the other occurring 4 years earlier in 1953.
In June of 2007, the 50th anniversary of the tornado was commemorated by the Fargo Forum, which ran a week-long series of stories on the tornado.