and the northwest United States. See also Western Pacific Railway References External links Brief history of the SI Roster of SI diesel locomotives Roster listing of SI wooden and steel cabooses Further reading Predecessors of the Union Pacific Railroad Former Class I railroads in the United States Railway companies established in 1941 Railway companies disestablished in 1987 Defunct Washington (state) railroads Defunct Idaho railroads American companies established in 1941 Standard gauge railways in the United States