Question: What did the Spokane and Inland Empire Railroad merge into that operated between 1970 and 1996?

full_context: Document 1: Chicago, Burlington and Quincy Railroad: The Chicago, Burlington and Quincy Railroad (reporting mark CBQ) was a railroad that operated in the Midwestern United States. Commonly referred to as the Burlington or as the Q, the Burlington Route served a large area, including extensive trackage in the states of Colorado, Illinois, Iowa, Kansas, Kentucky, Missouri, Montana, Nebraska, Wisconsin, Wyoming, and also in New Mexico and Texas through subsidiaries Colorado and Southern Railway, Fort Worth and Denver Railway, and Burlington-Rock Island Railroad. Its primary connections included Chicago, Minneapolis-St. Paul, St. Louis, Kansas City and Denver. Because of this extensive trackage in the midwest and mountain states, the railroad used the advertising slogans "Everywhere West", "Way of the "Zephyrs"", and "The Way West". It merged into Burlington Northern in 1970.
Document 2: Oregon, Washington and Idaho Railroad: The Oregon, Washington and Idaho Railroad built a 72.03 mi rail line along the right (north) bank of the Snake River between Riparia, Washington and Lewiston, Idaho. The company was incorporated in Oregon on August 8, 1903, and began operating its completed line on July 7, 1908 as an operating subsidiary of the Union Pacific Railroad (UP), which also controlled the Oregon Railroad and Navigation Company (OR&N) through Riparia. A portion of the preliminary work had been done by the Snake River Valley Railroad, which built a completed line along the Snake River below Riparia. Beginning on December 3, 1909, the Camas Prairie Railroad, a joint subsidiary of the OR&N and Northern Pacific Railway (NP), began operating the Oregon, Washington and Idaho Railroad (OW&I) as part of a line between Riparia and Grangeville, Idaho, including segments owned by the NP and subdidiary Clearwater Short Line Railway. On December 23, 1910, the property of the OW&I was conveyed to new UP subsidiary Oregon–Washington Railroad and Navigation Company, successor to the OR&N, but the Camas Prairie Railroad continued to operate it as agent.
Document 3: Great Northern Railway (U.S.): The Great Northern Railway (reporting mark GN) was an American Class I railroad. Running from Saint Paul, Minnesota, to Seattle, Washington, it was the creation of 19th-century railroad entrepreneur James J. Hill and was developed from the Saint Paul & Pacific Railroad. The Great Northern's (GN) route was the northernmost transcontinental railroad route in the U.S.
Document 4: Robert Krebs: Robert D. Krebs has headed three major United States railroads in succession, leading the Southern Pacific (SP) when it was acquired by Santa Fe Industries, rising to lead the resulting Santa Fe Pacific Corporation, and finally being chosen to head the new Burlington Northern Santa Fe (BNSF) when Santa Fe Pacific (the holding company for the Santa Fe railroad) merged with Burlington Northern.
Document 5: Chicago and North Western Transportation Company: The Chicago and North Western Transportation Company (reporting mark CNW) was a Class I railroad in the Midwestern United States. It was also known as the North Western. The railroad operated more than 5,000 miles (8,000 km) of track as of the turn of the 20th century, and over 12,000 miles (19,000 km) of track in seven states before retrenchment in the late 1970s. Until 1972, when the company was sold to its employees, it was named the Chicago and North Western Railway (or Chicago and North Western Railway Company).
Document 6: Spokane and Inland Empire Railroad: The Spokane and Inland Empire Railroad Company (S.&I.E.R.R.Co.) was an electrified interurban railway operating in Spokane, Washington and vicinity, extending into northern and central Idaho. The system originated in several predecessor roads beginning c. 1890, incorporated in 1904, and ran under its own name to 1929. It merged into the Great Northern Railway and later, the Burlington Northern Railroad, which operated some roads into the 1980s.
Document 7: High Bridge (Latah Creek): High Bridge, a railroad bridge over Latah Creek in Spokane, Washington, was constructed in 1972 by the Burlington Northern Railroad, following that railroad's creation in 1970 through the merger of the Chicago, Burlington & Quincy, Great Northern, Northern Pacific, and Spokane, Portland & Seattle railways. The bridge links the former Northern Pacific mainline with the former Great Northern and Spokane, Portland & Seattle lines to the west. The Latah Creek railroad bridge and two bridges carrying Interstate 90 and Sunset Highway cross High Bridge Park.
Document 8: Highland Park and Lake Burien Railway: The Highland Park and Lake Burien Railway was a branch of the Interurban System that went from Everett to Tacoma in Washington state. A branch came off about Spokane Street going west to near the Steel Mill. It went up nearly parallel to Delridge Way to White Center then on to Burien to end just north of "Kirks Feedstore". It had one passenger car and frequently had a flat car attached for it also carried freight.
Document 9: Northern Transcon: The Northern Transcon, a route operated by the BNSF Railway, traverses the most northerly route of any railroad in the western United States. This route was originally part of the Chicago, Burlington and Quincy Railroad, Northern Pacific Railway, Great Northern Railway and Spokane, Portland and Seattle Railway systems, merged into the Burlington Northern Railroad system in 1970.
Document 10: Burlington Northern Railroad: The Burlington Northern Railroad (reporting mark BN) was a United States-based railroad company formed from a merger of four major U.S. railroads. Burlington Northern operated between 1970 and 1996.
Document 11: Billings Depot: The Northern Pacific Billings Depot is a historic train depot in the Historic District of downtown Billings, Montana. The depot was constructed to serve as a passenger station for the Northern Pacific Railway, Great Northern and Chicago, Burlington and Quincy. All three railroad merged to form the Burlington Northern Railroad in 1970, along with the Spokane, Portland and Seattle Railway. In 1971 Amtrak took over passenger service throughout the country.
Document 12: Southern Pacific Transportation Company: The Southern Pacific (reporting mark SP) (or Espee from the railroad initials- SP) was a name of multiple American Class I railroads that existed from 1865 to 1998 and all operated in the Western United States. The names that represented the Southern Pacific were Southern Pacific Railroad, Southern Pacific Company and Southern Pacific Transportation Company.
Document 13: Conrail: Conrail, the Consolidated Rail Corporation, (reporting mark CR) , was the primary Class I railroad in the Northeastern United States between 1976 and 1999, when its routes were split between the CSX Corporation and Norfolk Southern Railway. Conrail, a portmanteau of "consolidated" and "rail" from the name of the company, operates now as a joint-subsidiary for some limited functions.
Document 14: Northern Securities Company: The Northern Securities Company was a short-lived American railroad trust formed in 1901 by E. H. Harriman, James J. Hill, J.P. Morgan and their associates. The company controlled the Northern Pacific Railway; Great Northern Railway; Chicago, Burlington and Quincy Railroad; and other associated lines. It was capitalized at $400 million, and Hill served as president.
Document 15: Frequency Changing Station: The Frequency Changing Station in Spokane, Washington is a building listed on the National Register of Historic Places. It was built by the Spokane and Inland Empire Railroad in 1908 to house electrical equipment used by the electric railway. Power was generated at the Nine Mile Falls dam and transmitted to the Frequency Changing Station. The station provided direct current to the streetcar network within the city of Spokane. To provide power to the rail network outside Spokane, the station converted a portion of the power to alternating current and fed it to a series of electrical substations spaced about 15 mi on the operating line. The substations then converted power back to direct current for the streetcars, but also sold power at 110 volts AC to the communities.
ground_truth: Burlington Northern Railroad