The worst tornado in U.S. history passes through eastern Missouri, southern Illinois, and southern Indiana, killing 695 people, injuring some 13,000 people, and causing $17 million in property damage. Known as the “Tri-State Tornado,” the deadly twister began its northeast track in Ellington, Missouri, but wreaked its worst damage in southern Illinois. More than 500 of the total 695 people who perished were killed there, including 234 in Murphysboro and 127 in West Frankfort. A tornado is a dark, funnel-shaped cloud containing violently rotating air that develops in climate conditions that, in the United States, are generally unique to the central and southern plains and the Gulf states. The rotating winds of tornadoes can attain velocities of 300 m.p.h., and its diameter can vary from a few feet to a mile. A tornado generally travels in a northeasterly distance at speeds of 20 to 40 m.p.h. and usually covers anywhere between one and more than 100 miles. The Tri-State Tornado of 1925 traveled 219 miles, spent more than three hours on the ground, devastated 164 square miles, had a diameter of more than a mile and traveled at speeds in excess of 70 m.p.h.