On this day: Mississauga train derailment forces evacuation of more than 200,000 people

It was late on a Saturday night–just turning to Sunday morning–more than four decades ago when the dark Mississauga sky lit up like never before.

And never again since.

A huge explosion at the Mavis Rd. rail crossing just north of Dundas St. W. sent the resulting orange fireball about 1,000 feet into the midnight sky.

The time was 11:56 p.m. on Nov. 10, 1979 and the growing city of Mississauga, with a new mayor named Hazel McCallion, was about to be forever changed.

Three minutes earlier, as a 106-car Toronto-bound train carrying 90 tonnes of chlorine and tankers full of other highly flammable materials including propane and butane sped by the Burnhamthorpe Rd. crossing, a red-hot set of train wheels fell off and flew 50 feet through the air.

The train wheels landed in the backyard of a Freeport Cr. resident.

Moments later, train cars began crashing into one another and 25 of them left the tracks.

The explosion was sudden, and deafening. It rocked numerous neighbourhoods in the immediate vicinity. And it awakened tens of thousands of Mississauga residents who had already gone to bed. Scores of others, meanwhile, were already at their windows, on their balconies and at the bottom of their driveways eyeballing the massive fireball and trying to figure out what had blown up.

At 11:57 p.m., every available piece of firefighting equipment in Mississauga, including dozens of fire trucks, was sent to the scene of the explosion and crippled train.

As people across the city were still trying to figure out exactly what had happened and what was ablaze, and just how serious the situation was, a second explosion–considerably more powerful than the first–rocked the city at 12:01 a.m. as Saturday gave way to Sunday.

The flash of light was seen by people as far away as Niagara Falls, Oshawa and Peterborough

“The noise awakens tens of thousands throughout Toronto. The blast was so powerful that one tanker is hurled a kilometre away,” Heritage Mississauga writes in its account of the historic event. “Firefighters do their best, but can make no impression on the raging flames. Eleven of the derailed tankers contain highly-explosive propane, and one tanker held the 90 tons of chlorine.”

43 yrs ago, over 200,000 people were safely evacuated following a train derailment in Msga. With partnerships, preparation & planning, The Mississauga Miracle was the largest peacetime evacuation in N. America at the time with no deaths reported as a result of the disaster. pic.twitter.com/9GLtuisqb7

— Peel Regional Police (@PeelPolice) November 10, 2022

In stages over the next several hours and day, the vast majority of Mississauga residents were evacuated from their homes, many kept from returning for nearly a week.

In all, more than 200,000 of the city’s 294,000 residents at the time were forced to leave their homes in what was, at the time, the largest peacetime evacuation in North American history.

Heritage Mississauga offers a full and detailed account of the entire ordeal, from the time the train left its starting point in Ohio earlier on Nov. 10, 1979 to nearly a week later when all residents finally returned to their homes to resume their lives.

The Mississauga train derailment changed the city–and other municipalities–in several ways, including making it a priority for the city to have a detailed, up-to-date emergency plan in place should disasters strike.