A tornado outbreak in Illinois

A destructive tornado outbreak affected much of the Midwestern United States on April 21, 1967, in particular the towns of Belvidere and Oak Lawn, Illinois, United States. It was the largest tornado outbreak of 1967 and has been described by NWS Chicago as "Northern Illinois' worst tornado disaster". The outbreak produced numerous and significant (F2+) tornadoes, with ten of them in Illinois alone. Included was one of just six documented violent (F4/F5) tornadoes in the Chicago metropolitan area since the area was first settled.