Question: The Spokane and Inland Empire Railroad Company later merged into a United States-based company formed from a merger of four what?
Context: 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. Student of Fortune was a United States-based company that provided an online tutoring marketplace.  The company was founded by Sean McCleese in 2006, shortly after graduating from Occidental College.  In an interview with "The Daily Trojan", McCleese described the way the company's site operated as being similar to eBay.  The company's site did not offer direct tutoring services, instead offering a channel to connect tutors and students.  Student of Fortune was located in Los Angeles, California, and was privately held, having taken no outside investment funds.  The firm was acquired by Chegg on August 19, 2011.  On 15 July 2013 Chegg announced that it would close down studentoffortune.com on 15 August 2013. San Bernardino is a city located in the Riverside-San Bernardino metropolitan area (sometimes called the "Inland Empire").  It serves as the county seat of San Bernardino County, California, United States.  As one of the Inland Empire's anchor cities, San Bernardino spans 81 sqmi on the floor of the San Bernardino Valley and has a population of 209,924 as of the 2010 census.  San Bernardino is the 17th-largest city in California and the 100th-largest city in the United States.  San Bernardino is home to numerous diplomatic missions for the Inland Empire, being one of four cities in California with numerous consulates (the other three being Los Angeles, San Diego and San Francisco).  The governments of Guatemala and Mexico have also established their consulates in the downtown area of the city. The Hercules Gas engine company was a United States-based company which first produced buggies.  It later was one of the top producers of gasoline engines, including to power cement mixers. The South Carolina Canal and Rail Road Company was chartered under act of the South Carolina General Assembly of December 19, 1827.  The company operated its first 6 mi line west from Charleston, South Carolina in 1830.  The railroad ran scheduled steam service over its 136 mi line from Charleston, South Carolina, to Hamburg, South Carolina, beginning in 1833.  Some sources referred to the railroad informally as the "Charleston and Hamburg Railroad", a reference to its end points, but that was never its legal name.  In 1839, The Louisville, Cincinnati and Charleston Railroad Company, which had built no track of its own, gained stock control of The South Carolina Canal and Rail Road Company, which continued to operate under that name.  In 1844, The South Carolina Canal and Rail Road Company merged with The Louisville, Cincinnati and Charleston Railroad Company.  The merged company changed its name to South Carolina Railroad Company under an act of the South Carolina legislature dated December 19, 1843. 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. IvyExec.com is a United States-based company that runs an online professional network for executives as well as recruitment, market research, marketing and advertising services.  Ivy Exec, Inc. was founded in 2006 by a team of Columbia Business School alumni and is based in New York, New York.  Ivy Exec helps various professionals and MBAs find jobs with companies.  The company has over 800,000 members. 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. Nine Mile Falls Dam is a dam on the Spokane River, in the unincorporated community of Nine Mile Falls, Washington.  It was built on the site of the falls in 1908, creating Nine Mile Reservoir.  The dam was designed by the New York engineering firm of Sanderson & Porter, and originally constructed to satisfy the power needs of the Spokane and Inland Empire Railroad interurban trolley lines. The Syracuse, Ontario and New York Railway was founded in 1883 and had a line that ran between Syracuse, New York and Earlville, New York, a distance of 45.5 mi .  The company formed from the Syracuse, Chenango and New York Railroad Company.  Beginning on July 1, 1890 it operated as the Chenango County, New York branch of the West Shore Railroad.  On April 2, 1891, the railroad and property of the Syracuse Ontario and New York Railway Company were formally leased, for the term of its corporate existence, to the West Shore Railroad Company on June 30, 1891.  Later, ownership was transferred to the New York Central Railroad (NYCRR).
Answer: major U.S. railroads