The arrival of the Grand Trunk Railway at the end of the 19th Century drew industrial investors to Saint-Laurent. However, Saint-Laurent's evolution was due mainly to its superior geographic location and the major communication lines that progressively developed on Montréal Island.
In fact, Saint-Laurent is served by major road arteries including Félix-Leclerc Autoroute (Trans-Canada Highway), Chomedey Autoroute, Métropolitaine Autoroute, Côte-de-Liesse Autoroute, Laurentides Autoroute and Décarie Autoroute. Moreover, it has benefited greatly from its location near Dorval and Mirabel airports, as well as the freight yards operated by the country's two leading railway companies, Canadian National and Canadian Pacific.
The City also owes its success to the conditions offered to the major companies that have settled on its territory (selected affordable land, tax transfers to attract newcomers), as well as the relationships it maintains with its industries.
Starting in the middle of the 20th Century, Saint-Laurent experienced an industrial boom which, over a period of just a few years, allowed it to garner the position as the second leading industrial city in Quebec.
Numerous industries gradually settled in Saint-Laurent, specifically major companies operating in the realm of aerospace, which ensured sustained economic viability for the City. In the 1950's around forty companies were settled. In 1970, Saint-Laurent became the second-leading industrial city in Quebec with more than 400 companies. It continues to hold this title today, with more than 70% of its territory dedicated to business development.
At the end of the 20th Century, the industrial sector continued to grow at an astonishing rate. Over a period of just three years, specifically between 1998 and 2001, the sector created 12,000 new jobs in Saint-Laurent. In 2002, a total of 3,608 companies provided employment for 112,797 – a remarkable feat considering the municipality's population of 77,391 residents.
To ensure the continuation of this growth, the City opened a business park dedicated to research and development, specifically the Technoparc. Today, Saint-Laurent's industrial parks cover an area of 201 million square feet, 100 million of which have access to municipal services and are ready for industrial development.