1974 Super Outbreak
en.wikipedia.org

... The 1974 Super Outbreak was one of the most intense tornado outbreaks on record, occurring on April 3-4, 1974, across much of the United States. It was one of the deadliest tornado outbreaks in U.S history. It was also the most violent tornado outbreak ever recorded, with 30 violent (F4 or F5 rated) tornadoes confirmed.

From April 3"4, there were 148 tornadoes confirmed in 13 U.S. states and the Canadian province of Ontario.[nb 1] In the United States, the tornadoes struck Illinois, Indiana, Michigan, Ohio, Kentucky, Tennessee, Alabama, Mississippi, Georgia, North Carolina, Virginia, West Virginia, and New York. The outbreak caused roughly $600 million USD (equivalent to $3.83 billion in 2024) in damage.[4]

The outbreak extensively damaged approximately 900 sq mi (2,331 km2) along a total combined path length of 2,600 mi (4,184 km).[3][5] At one point, as many as 15 separate tornadoes were occurring simultaneously.[3][6] ...