The super outbreak was one of the largest 24 hour tornado outbreaks in history.
Between April 3 and April 4, 1974, there were 148 confirmed tornadoes in 13 states.
Hundreds of communities were hit. Among the very worst was a city in Ohio where more than 30 people were killed and over 1,000 were injured.
In Canada, an F3 tornado struck Windsor, Ontario, killing 9 people.
In total, there were more than 330 deaths and more than 5,000 injuries.
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