A-15 begins at the end of Interstate 87 at the United States border at Saint-Bernard-de-Lacolle and extends via Montreal to Sainte-Agathe-des-Monts with an eventual continuation beyond Mont-Tremblant.

It was built on a wide expanse of vacant land, donated to the city by the Décarie estate on the condition that a streetcar line would be established.

The decommissioning of the streetcar system in 1959 left the right-of-way as an obvious choice for a highway and so the Décarie Autoroute was dug there.

Following the conversion from streetcar line to the highway, the Décarie estate sued the city but was unable to prevail because it did not document its case well enough for the nevertheless sympathetic court.

Décarie Boulevard itself continues; from Monkland Avenue south to Saint Jacques Street past the McGill University Health Centre Glen Campus superhospital; and from Autoroute 40 north into Montreal past Du College Station and Côte-Vertu Station/Norgate shopping centre to Poirier Street.

[4] Over the next years, it was extended north to Sainte-Agathe-des-Monts as a new connection to touristic and skiing destinations in the Laurentides including in Saint-Sauveur, Sainte-Adèle and Estérel.

On June 18, 2000, the southern portion of the Boulevard du Souvenir overpass in Laval (which crosses over Quebec Autoroute 15), under reconstruction, collapsed into the roadway, killing one and injuring two when cars were crushed underneath the structure.

On July 14, 1987, a sudden torrential downpour caused by an HP supercell thunderstorm dumped over 100 millimetres (3.9 inches) of rain in just over one hour across the city.

On July 5, 2005, another torrential downpour flooded portions of the Expressway after several manhole covers blew open from the storm sewers below them being overloaded.