On April 3, 1974, 148 tornadoes crossed 13 states in 16 hours and killed 335 people, forcing a rebuild of how the country warns for severe storms.
On this day in 1974, the first tornado touched down in Indiana at about 9:30 in the morning. By the time the last one lifted in North Carolina the next morning, 148 tornadoes had crossed 13 states and part of Ontario. Thirty of them were rated F4 or F5, more violent tornadoes than any outbreak before or since. The storms killed 335 people, injured more than 5,000, and left a damage path measured at 2,500 miles.
Warning technology in 1974 was thin. Forecasters worked from 1957 era radar that showed rainfall intensity but not rotation, and word reached most households through radio and television or not at all. Several towns were struck twice within an hour by tornadoes following nearly identical tracks.
The response reshaped the National Weather Service. The modernization that followed brought Doppler radar, restructured field offices and the public education campaigns that taught a generation what a watch and a warning mean. That system now delivers the alert, which leaves the household to decide in advance where it goes. Picking that spot before the sky turns is the whole of what to do when a tornado hits, and it matters most in the places most at risk of tornadoes.