I read that the longest tornado on record happened in Illinois and was on the ground for seven hours. Is that true?
While it’s true that the longest tornado on record occurred in Illinois, your estimate its of duration is off by a factor of two. The Tri-State Tornado of March 18, 1925, is this nation’s deadliest single tornado. . For nearly three-and-one-half hours the twister, traveling in excess of 60 m.p.h., cut a 219-mile long path of death and destruction from southeast Missouri to southwest Indiana. Nearly 700 people were killed and at least 2,000 were injured. The tornado began around 1 p.m. near Ellington, Mo., then crossed into Illinois north of Cape Girardeau. It finally entered Indiana northwest of Evansville before dissipating 10 miles northeast of Princeton, Indiana just after 4:15 p.m.