In the last 50 years, the following tornadoes caused the most death:
April 3-4, 1974 — The "Super Outbreak," the worst tornado outbreak in recent U.S. history, 330 dead.
In a two-day stretch, approximately 147 tornadoes touched down in 13 U.S. states and Canada killing 306 people in one day alone.
On April 3, 1974, the main day of the two-day "Super Outbreak," tornadoes killed 308 people.
Forth-eight of the tornadoes were killers. Seven produced damage rated F5 — the maximum possible.
April 11, 1965 — Called the original "Palm Sunday Outbreak" tornadoes were to blame for 260 deaths.
Feb. 21, 1971 — An outbreak of several strong and violent tornadoes occurred across the Arkansas, Louisiana, Mississippi region, with three separate violent (F4 or F5) tornadoes occurring. A total of 121 people were killed by these three tornadoes, over 100 of which were in the Delta counties of Mississippi. More than 1200 people were injured.