The Great Northern Z-1 was a class of ten electric locomotives built for the Great Northern Railway They were used to work the route through the second Cascade Tunnel. They were built between 1926–1928 by Baldwin Locomotive Works, with Westinghouse electrics, and stayed in service until dieselisation in 1956. Each was of 1,830 horsepower (1,360 kW) with a 1-D-1 wheel arrangement, although they were always used in coupled pairs.