The line, originally named the Spokane International Railway, was built by local businessman and railroader Daniel Chase Corbin following an agreement between him and the CP, with CP agreeing to fund much of the line's construction and to secure the loan by holding the new line's bonds.
The SI was reorganized October 1, 1941, following financial difficulties and receivership during the Great Depression. The line was renamed the Spokane International Railroad as part of the restructuring agreement until the 1950s.
On October 6, 1958, the Union Pacific Railroad (UP) took control of Spokane International Railroad.[2] In 1962 UP leased SI's 11 ALCO RS-1 locomotives for operation. The locomotives were later repainted to UP's yellow and gray paint scheme, but retained their SI lettering. Also in 1962, UP sold four of its older steel cabooses to SI. These were also painted in UP's yellow scheme, but received SI lettering and numbers. After UP's 1958 control of SI, Union Pacific continued to lease SI for operation. On December 31, 1987, Union Pacific formally merged SI into its corporate structure.
At the end of 1960 SI operated 150 miles (240 km) of road on 190 miles (310 km) of track; that year it reported 141 million net ton-miles of revenue freight and zero passengers.
The line remains in operation as the Union Pacific's Spokane Subdivision, an important connection between southern British Columbia and the northwest United States.[3][4]
^Kelly, Bruce E. (March 19, 2021). "Will CP Enter the U.S. Northwest?". Railway Age. Retrieved August 3, 2021. This hypothetical transaction would involve UP's 138-mile Spokane Subdivision from the U.S./Canada border station of Eastport, Idaho, to a connection with BNSF Railway just south of UP's SI Yard in Spokane, Wash....
Railroads in italics meet the revenue specifications for Class I status, but are not technically Class I railroads due to being passenger-only railroads with no freight component.