Until about the 1970s there were 4 tracks at the station. Track 1 (the southernmost track, closest to the station) was removed. In the 1980s the crossover from North Junction into the station (track 4) was removed, but was restored in 1999 when the Blainville train line (now Saint-Jérôme line) started downtown service. It wasn't until 2003, however, that Saint-Jérôme trains stopped at Montréal-Ouest. At that point, the northernmost track (now signed as Track 3) was served by an island platform, which also served track 2.