On this day in 1947, an F4 tornado tracked for 40 miles from near Warren, OH, through Sharon, PA lifting near Mercer, PA. This tornado had an almost identical track to the infamous May 31, 1985, Niles OH to Wheatland, PA F5. Six people were killed, and 340 were injured as numerous homes and factories were leveled. Source: Significant Tornadoes 1880-1989.