The following is a brief history of the North American rail system, mainly through major changes to Class I railroads, the largest class by operating revenue.

1910 July 1: The first year of classification by operating revenue begins. July 1: The property of the independent Chicago, Cincinnati and Louisville Railroad, which entered receivership on February 14, 1908,ICC (1910), pp. 160-161 is conveyed to the Chesapeake and Ohio Railway of Indiana,Interstate Commerce Commission, 24 Val. Rep. 451 (1929): Valuation Docket No. 477, The Chesapeake and Ohio Railway Company of Indiana a subsidiary of the Chesapeake and Ohio Railway.ICC (1911), p. 686 December 23: The property of the Oregon Railroad and Navigation Company is sold to the Oregon-Washington Railroad and Navigation Company,Interstate Commerce Commission, 44 Val. Rep. 1 (1933): Valuation Docket No. 329, Oregon-Washington Railroad & Navigation Company remaining a subsidiary of the Oregon Short Line Railroad (Union Pacific Railroad system).ICC (1910), p. 238ICC (1911), p. 716

1911 January 1: The Chicago, Terre Haute and Southeastern Railway begins operations after acquiring the properties of the Southern Indiana Railway and subsidiary Chicago Southern Railway, which entered receivership on August 19ICC (1910), pp. 170-171 and August 25, 1908, respectively.ICC (1910), pp. 204-205Interstate Commerce Commission, 97 I.C.C. 535 (1925): Valuation Docket No. 41, Chicago, Terre Haute and Southeastern Railway Company February: The New York Central Railroad sells half of its majority interest in the Rutland Railroad to the New York, New Haven and Hartford Railroad.The Earning Power of Railroads, 1916, p. 235 April 20: The Blacklick and Yellow Creek Railroad changes its name to Cambria and Indiana Railroad (not yet Class I).Interstate Commerce Commission, 130 I.C.C. 412 (1927): Valuation Docket No. 498, Cambria and Indiana Railroad Company June 30: The first year of classification by operating revenue ends. There are 177 Class I railroads, including two Canadian companies (Canadian Pacific Railway and Canadian Northern Railway) not included in any totals by the ICC, and a separate listing for "Canadian Pacific Lines in Maine" (leased lines of the International Railway of Maine, Aroostook River Railroad, and Houlton Branch Railroad). Grand Trunk Railway of Canada lessor Atlantic and St. Lawrence Railroad is also listed as a Class I railroad.ICC (1911) July: The Missouri, Kansas and Texas Railway gains control of the Wichita Falls and Northwestern Railway (not yet Class I). July 1: Pennsylvania Railroad subsidiaries Cleveland, Akron and Columbus Railway and Cincinnati and Muskingum Valley Railroad, the latter not Class I, merge to form the Cleveland, Akron and Cincinnati Railway.Interstate Commerce Commission, 23 Val. Rep. 365 (1929): Valuation Docket No. 386, Pennsylvania Company and its Leased Lines July 1: The Illinois Central Railroad begins operating the property of former subsidiary Indianapolis Southern Railroad, purchased at foreclosure.Poor's Intermediate Manual of Railroads, 1917, p. 309 July 21: The Chicago and Eastern Illinois Railroad buys the property of subsidiary Evansville and Terre Haute Railroad.Interstate Commerce Commission, 31 Val. Rep. 1 (1929): Valuation Docket No. 202, Chicago and Eastern Illinois Railroad Company September 15: The Bingham and Garfield Railway completes its main line.Interstate Commerce Commission, 106 I.C.C. 450 (1925): Valuation Docket No. 267, Bingham & Garfield Railway Company It will be listed as Class II in 1912ICC (1912) and Class I in 1913.ICC (1913), p. 695 September 16: The International and Great Northern Railway begins operating the former International and Great Northern Railroad,Interstate Commerce Commission, 149 I.C.C. 587 (1928): Valuation Docket No. 355, International and Great Northern Railway Company et al. in receivership since February 27, 1908.ICC (1911), p. 710 November: The Louisville and Nashville Railroad and St. Louis and San Francisco Railroad jointly buy control of the New Orleans, Mobile and Chicago Railroad, predecessor of the Gulf, Mobile and Northern.The Earning Power of Railroads, 1914, p. 395 December 28: The property of Atchison, Topeka and Santa Fe Railway subsidiary Santa Fe, Prescott and Phoenix Railway is conveyed to AT&SF lessor California, Arizona and Santa Fe Railway.Interstate Commerce Commission, 127 I.C.C. 1 (1928): Valuation Docket No. 625, Atchison, Topeka and Santa Fe Railway Company et al.

1912 January 1: Pennsylvania Railroad subsidiary Pennsylvania Company leases the Cleveland, Akron and Cincinnati Railway. January 1: The Minneapolis and St. Louis Railroad acquires the property of the Iowa Central Railway,Interstate Commerce Commission, 137 I.C.C. 761 (1928): Valuation Docket No. 510, Minneapolis & St. Louis Railroad Company formerly independent. March 20: The Sunset Railroad, controlled jointly by the Atchison, Topeka and Santa Fe Railway and Southern Pacific Company, merges with lessor Sunset Western Railway to form the Sunset Railway (no longer Class I).Moody's (1976), p. 32 April 4: The Crystal City and Uvalde Railroad is renamed San Antonio, Uvalde and Gulf Railroad (not yet Class I). June 30: The Sunset Railroad is demoted from Class I to II; it will never return to the former classification. The Kansas City, Mexico and Orient Railway also becomes Class II, since Texas subsidiary Kansas City, Mexico and Orient Railway of Texas had been listed as a lessor in 1911, but is now listed as an operating subsidiary, and the revenues of the parent alone are not enough to qualify for Class I. On the other hand, the Detroit and Toledo Shore Line Railroad, Oahu Railway and Land Company, and Western Pacific Railroad are newly listed as Class I. The Chesapeake and Ohio Railway begins including data for subsidiary Chesapeake and Ohio Railway of Indiana with its own data. With the loss of the Cleveland, Akron and Cincinnati Railway, Evansville and Terre Haute Railroad, Indianapolis Southern Railroad, Iowa Central Railway, and Santa Fe, Prescott and Phoenix Railway, and electrification of the Spokane and Inland Empire Railroad, the number of Class I railroads drops from 177 in 1911 to 171 as of June 30, 1912.ICC (1911, 1912) October 1: The Delaware, Lackawanna and Western Railroad leases subsidiary Syracuse, Binghamton and New York Railroad.ICC (1914), p. 707 December 9: Canadian Northern Railway subsidiary Duluth, Winnipeg and Pacific Railway completes its lineInterstate Commerce Commission, 141 I.C.C. 503 (1928): Valuation Docket No. 856, Duluth, Winnipeg and Pacific Railway Company et al. and becomes Class I.ICC (1913), p. 696 December 24: The property of the Chicago, Milwaukee and Puget Sound Railway is conveyed to parent Chicago, Milwaukee and St. Paul Railway.Interstate Commerce Commission, 44 Val. Rep. 441 (1933): Valuation Docket No. 1072, Chicago, Milwaukee and St. Paul Railway Company et al.

1913 January 1: The Chicago, Peoria and St. Louis Railroad begins operating the former Chicago, Peoria and St. Louis Railway of Illinois,Commercial Newspaper Company, The Manual of Statistics, 1920, p. 965 in receivership since July 1, 1909.ICC (1911), p. 709 May 1: The Denver and Salt Lake Railroad begins operating the former Denver, Northwestern and Pacific Railway,Interstate Commerce Commission, 119 I.C.C. 483 (1926): Valuation Docket No. 770, Denver and Salt Lake Railroad Company in receivership since May 2, 1912.ICC (1912), p. 665 May 28: The Butte, Anaconda and Pacific Railway begins electric service.Engineering & Mining Journal, Volume 97, No. 11, p. 559: Butte, Anaconda & Pacific Electrification, March 14, 1914 June 30: The Arizona and New Mexico Railway, Bingham and Garfield Railway, Florence and Cripple Creek Railroad, Lehigh and New England Railroad, Missouri and North Arkansas Railroad, Missouri, Oklahoma and Gulf Railway, and Spokane International Railway are reclassified from II to I, and the new Duluth, Winnipeg and Pacific Railway is also Class I. The Missouri, Kansas and Texas Railway of Texas starts including its data with parent Missouri, Kansas and Texas Railway, and, with the disappearance of the Chicago, Milwaukee and Puget Sound Railway and Syracuse, Binghamton and New York Railroad, the number of Class I railroads rises from 171 in 1912 to 176 as of June 30, 1913.ICC (1912, 1913) December 31: The Buffalo and Susquehanna Railroad is reorganized under the same name,Interstate Commerce Commission, 36 Val. Rep. 199 (1931): Valuation Docket No. 340, Buffalo & Susquehanna Railroad Corporation et al. having been in receivership since July 23, 1910. Former parent Buffalo and Susquehanna Railway (Class II), also in receivership (since May 3, 1910),ICC (1913), p. 674 remains independent, and is reorganized as the Wellsville and Buffalo Railroad (Class II) on December 14, 1915ICC (June 30, 1916), pp. 677, 696 and abandoned in November 1916.Arthur Stone Dewing, The Financial Policy of Corporations, Volume 1 (Corporate Securities), p. 111

1914 January 1: The Cleveland, Cincinnati, Chicago and St. Louis Railway begins recording its lease of the Peoria and Eastern Railway, which dates from April 1, 1890, as such.Interstate Commerce Commission, 28 Val. Rep. 90 (1929): Valuation Docket No. 264, The Cleveland, Cincinnati, Chicago and St. Louis Railway Company and its Leased Lines Previously the P&E was listed as Class I.ICC (1913), p. 679 March 1: The Detroit, Toledo and Ironton Railroad begins operating the former Detroit, Toledo and Ironton Railway, which had been in receivership since February 1, 1908.Interstate Commerce Commission, 141 I.C.C. 115 (1928): Valuation Docket No. 857, Detroit, Toledo and Ironton Railroad Company et al. As a consequence of this reorganization, the DT&I no longer controls the Ann Arbor Railroad.ICC (1913), p. 675 March 30: The Boston and Maine Railroad sells its controlling share in the Maine Central Railroad.Poor's Intermediate Manual of Railroads, 1917, pp. 1019-1020 April 7: The Grand Trunk Pacific Railway is completed. May 1: The Missouri, Kansas and Texas Railway leases subsidiary Wichita Falls and Southern Railway (not yet Class I) to Texas subsidiary Missouri, Kansas and Texas Railway of Texas.290 I.C.C. 303 (1954): Finance Docket No. 18163, Wichita Falls & Southern Railroad Company et al. Abandonment, etc. June 1: New York Central and Hudson River Railroad subsidiary Toledo and Ohio Central Railway buys control of the Kanawha and Michigan Railway from joint owners Lake Shore and Michigan Southern Railway (also a NYC subsidiary) and Chesapeake and Ohio Railway.Poor's Intermediate Manual of Railroads, 1917, p. 493 June 5: Atchison, Topeka and Santa Fe Railway subsidiary Southern Kansas Railway of Texas is renamed Panhandle and Santa Fe Railway. June 30: Despite the loss of the Peoria and Eastern Railway, the number of Class I railroads remains at 176, its 1913 value, since Grand Trunk Railway of Canada lessor Chicago, Detroit and Canada Grand Trunk Junction Railroad, which reports separately, is raised from Class II to I.ICC (1913, 1914) July 1: Atchison, Topeka and Santa Fe Railway subsidiary Pecos and Northern Texas Railway is leased in part to the Gulf, Colorado and Santa Fe Railway and Panhandle and Santa Fe Railway, being split at Sweetwater. July 6: The Kansas City, Mexico and Orient Railroad begins operating the former Kansas City, Mexico and Orient Railway,Interstate Commerce Commission, 135 I.C.C. 217 (1927): Valuation Docket No. 1050, Kansas City, Mexico and Orient Railroad Company in receivership since March 7, 1912.ICC (1914), p. 730 Texas subsidiary Kansas City, Mexico and Orient Railway of Texas is in receivership from March 9, 1912, to July 8, 1914. July 29: The Pennsylvania Railroad leases subsidiary Northern Central Railway.