Read more: Weather, Historic, Tornado, Deadliest, History
Most of the deadliest tornadoes in U.S. history occurred prior to 1950. That was largely because the ability to provide advance warning that a tornado was immenent was nonexistant. But with the advent of not only better weather predicting techniques but warning systems such as horns and sirens within communities, casualities from tornadoes were significantly decreased because better advance warning was possible. And with the development of Doppler radar, the warning got even better, further reducing the death toll and injuries that had been associated with these violent storms in the past.
Below is a list of the 10 deadliest tornadoes in America's history according to the Tornado Project Online!
| Location | Date | Time of day | Dead | Injured | F scale | Towns hit |
| Missouri, Illinois and Indiana | March 18, 1925 | 1:01 p.m. | 695 | 2,027 | F5 | Murphysboro, Gorham, DeSoto |
| Louisiana and Mississippi | May 7, 1840 | 1:45 p.m. | 317 | 109 | unknown | Nachez |
| Missouri and Illinois | May 27, 1896 | 6:30 p.m. | 255 | 1,000 | F4 | St. Louis and East St. Louis |
| Mississippi | April 5, 1936 | 8:55 p.m. | 216 | 700 | F5 | Tupelo |
| Georgia | April 6, 1936 | 8:27 a.m. | 203 | 1,600 | F4 | Gainesville |
| Texas, Oklahoma and Kansas | April 9, 1947 | 6:05 p.m. | 181 | 970 | F5 | Glazier, Higgins, Woodward |
| Louisiana and Mississippi | April 24, 1908 | 11:45 a.m. | 143 | 770 | F4 | Amite, Pine, Purvis |
| Wisconsin | June 12, 1899 | 5:40 p.m. | 117 | 200 | F5 | New Richmond |
| Michigan | June 8, 1953 | 8:30 p.m. | 115 | 844 | F5 | Flint |
| Texas | May 11, 1953 | 4:10 p.m. | 114 | 597 | F5 | Waco |
