Vaudreuil–Hudson line

Service on this line started in 1887. Service began with local stops between Montreal and Rigaud being added to trains running between Montreal and Ottawa. Over time, as the population of the western part of the Island of Montreal increased, Canadian Pacific established a dedicated commuter service with several stops on the Island of Montreal and off the western tip of the Island. Over the past 50 years, service patterns on the line have not changed all that much. The average number of weekday round trips has hovered around 12, with weekend and holiday service averaging 3 or 4 trips depending on whether the day is Saturday or Sunday.

The commuter line was owned and operated by Canadian Pacific until October 1, 1982. On that date, management and ownership of the commuter trains was transferred to the publicly owned Montreal Urban Community Transit Commission (STCUM). The STCUM set fares and schedules, and assumed ownership of the equipment (passenger cars and locomotives) that Canadian Pacific had used to operate the service. Canadian Pacific continued to provide the tracks, stations, storage, maintenance, and train crews needed to keep the line running. For Montreal commuters, the transfer of ownership was positive because the trains were integrated into the bus and metro system. Over time, the commuter line was upgraded with the purchase of new equipment and renovated stations. The line was transferred to the newly formed Agence métropolitaine de transport (AMT) on January 1, 1996.

On July 1, 2010, service to Rigaud was discontinued, as the town of Rigaud was unable to justify a $300,000 annual fee, almost double the previous annual fee of $160,000 required by the AMT to maintain train service for a handful of users.[5] The line now ends at Hudson; the 13-km distance between Rigaud and Hudson represented some 17% of the line's total length. At this time the line was renamed: "Dorion" was replaced by "Vaudreuil" in reference to the terminus for most runs, and "Rigaud" was replaced by "Hudson" in reference to the terminus for the extended service.[6]

On June 1st, 2017, the AMT was dissolved and replaced by two new governing bodies, the Autorité régionale de transport métropolitain (ARTM) and the Réseau de transport métropolitain (RTM). The RTM took over all former AMT services, including this line.

In May 2018, the RTM formally re-branded itself as Exo; and renamed each line with a number and updated colour. The Vaudreuil–Hudson line became exo1, and the red line colour was updated to a lighter pastel shade of red.