Tri-State Tornado of 1925, also called Great Tri-State Tornado, tornado, the deadliest in U.S. history, that traveled from southeastern Missouri through southern Illinois and into southwestern Indiana on March 18, 1925. The storm completely destroyed a number of towns and caused 695 deaths.

Tri-State Tornado of 1925 Path of the Tri-State Tornado of 1925, a massive storm that traveled through three states on March 18, 1925, covering 219 miles (352 km) in about 3.5 hours. With winds of about 300 miles (480 km) per hour, the storm completely leveled farms and towns in its path, injuring more than 2,000 individuals and claiming 695 lives. Encyclopædia Britannica, Inc./Kenny Chmielewski

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The tornado materialized about 1:00 pm local time in Ellington, Missouri. It caught the town’s residents by surprise, as the weather forecast had been normal. (To prevent panic among the public, tornado forecasting was not practiced at the time, and even the word “tornado” had been banned from U.S. weather forecasts since the late 19th century.) The storm moved quickly to the northeast, speeding through the Missouri towns of Annapolis, Biehle, and Frohna and killing 11 people before crossing the Mississippi River into southern Illinois, where it virtually destroyed the towns of Gorham, De Soto, and Murphysboro, among others. Murphysboro was the hardest-hit area in the tornado’s path, with 234 fatalities. After killing more than 600 people in Illinois, the tornado crossed the Wabash River into Indiana, where it demolished the towns of Griffin, Owensville, and Princeton and devastated about 85 farms in between. Having taken 71 lives in Indiana, the storm dissipated about 4:30 pm approximately 3 miles (5 km) southwest of Petersburg.

tornado forecasting Learn how the Tri-State Tornado of 1925 made meteorologists use the word tornado in their forecasts. Encyclopædia Britannica, Inc. See all videos for this article

With winds of roughly 300 miles (480 km) per hour, which would classify it as an EF5 tornado in the Enhanced Fujita Scale, the tornado lasted 3.5 hours and traveled 219 miles (352 km)—setting records for both duration and distance. Its width of up to 1 mile (1.6 km), average speed of almost 62 miles (100 km) per hour, and peak speed of 73 miles (117 km) per hour also make it one of the largest and fastest tornadoes in U.S. history. In addition to the 695 casualties, there were more than 2,000 injured survivors, as well as thousands who were left homeless and without food. Fires, looting, and theft in the tornado’s aftermath exacerbated its effects.