The Mississauga train derailment occurred on November 10, 1979, in Mississauga, Ontario, Canada, when a CP Rail freight train carrying hazardous chemicals derailed and caught fire. More than 200,000 people were evacuated in the largest peacetime evacuation in North America until Hurricane Katrina. The fire was caused by a failure of the lubricating system. No deaths resulted from the incident.

The Canadian Pacific Railway (reporting marks CP, CPAA, MILW, SOO), also known simply as Canadian Pacific and formerly as CP Rail (1968–1996), is a Canadian Class I railway incorporated in 1881. The railway is owned by Canadian Pacific Railway Limited, which began operations as legal owner in a corporate restructuring in 2001.Headquartered in Calgary, Alberta, it owns approximately 20,100 kilometres (12,500 mi) of track in seven provinces of Canada and into the United States, stretching from Montreal to Vancouver, and as far north as Edmonton. Its rail network also serves Minneapolis–St. Paul, Milwaukee, Detroit, Chicago, and Albany, New York in the United States.

The railway was first built between eastern Canada and British Columbia between 1881 and 1885 (connecting with Ottawa Valley and Georgian Bay area lines built earlier), fulfilling a commitment extended to British Columbia when it entered Confederation in 1871; it was Canada's first transcontinental railway. Primarily a freight railway, the CPR was for decades the only practical means of long-distance passenger transport in most regions of Canada, and was instrumental in the settlement and development of Western Canada. The CPR became one of the largest and most powerful companies in Canada, a position it held as late as 1975.The company acquired two American lines in 2009: the Dakota, Minnesota and Eastern Railroad (DM&E) and the Iowa, Chicago and Eastern Railroad (IC&E). The trackage of the IC&E was at one time part of CP subsidiary Soo Line and predecessor line The Milwaukee Road. The combined DM&E/IC&E system spanned North Dakota, South Dakota, Minnesota, Wisconsin, Nebraska and Iowa, with two short stretches into Kansas City, Missouri, and Chicago, Illinois.

It is publicly traded on both the Toronto Stock Exchange and the New York Stock Exchange under the ticker CP. Its U.S. headquarters are in Minneapolis. As of January 14, 2022, the largest shareholder of Canadian Pacific stock is TCI Fund Management Limited, a London-based hedge fund that owns 8.38% of the company.As of early 2022, the railroad is attempting to purchase the Kansas City Southern Railway. If approved by the US Surface Transportation Board, the combined "Canadian Pacific Kansas City Limited" will form the only railroad serving all of North America (Canada, Mexico and the United States).