Deux-Montagnes (also designated exo6 and formerly Red Line) was an electrified commuter rail line in Greater Montreal, Quebec, Canada. It was owned by Exo, the organization that operates public transport services throughout the Montreal area. The line was created in 1918 as a Canadian Northern Railway (CNoR) service. Canadian National Railway (CN) ran the line starting in 1923 following the merger of CNoR into CN. CN transferred the Deux-Montagnes Line to the Société de transport de la communauté urbaine de Montréal (STCUM) on July 1, 1982. The line was refurbished from 1992 to 1995. It was transferred to the RTM's predecessor agency, the Agence Métropolitaine de transport (AMT) on January 1, 1996. The RTM assumed current operation of the line upon its establishment on June 1, 2017. The RTM rebranded its commuter services "exo" in 2018. On May 11, 2020, service between Bois-Franc and Montreal Central Station was closed due to the construction of Réseau express métropolitain (REM). On December 31, 2020, the Deux-Montagnes line closed permanently in favour of REM service which operates along the same route. On November 17, 2025, the Deux-Montagnes branch of the REM officially opened to passenger service, replacing the Exo-6 service Route Map: Rolling Stock: CN Electric Multiple unit Electric Boxcab Locomotive & VIA Lightweight coaches Class Z-5a - GE Steeple-Cab Locomotive Bombardier MR-90 EMU (separate add-on) pricing: £19.99 or £24.99
