To operate the Mount Royal Tunnel in Montreal without steam, the Canadian Northern electrified this line with 2,400 Volts DC and ordered six boxcab locomotives from GE. At the same time, the Butte, Anaconda & Pacific did the same and so both railroads used the same equipment and similar locomotives. The locomotives built for the Canadian Northern were designated type GE 0440-E-166-4-GE-228-A by the manufacturer and delivered in 1917. They got the class designation Z-1-a and still retained it when they became part of the Canadian National in 1919. The first one was only retired in 1993 after 76 years in service. The other five followed in 1995 and four are preserved on static display.