On November 10, 1979 a freight train derailed. 24 of 106 railcars went off the tracks just north of Dundas St at Mavis Rd. The railcars contained chemicals such as propane and chlorine.
As a result a mass evacuation was order for Mississauga. It affected 250 000 people.
This was a significant event in the history of Mississauga
Location of the train derailment Dundas near Mavis
Train Derailment Plaque put up by Heritage Mississauga