March 2, 1833 
First United States railroad land grant law, transferring Michigan & Illinois Canal land grant to a railroad – but in the end it was never utilized.

Jan 1849
Aspinwall hired Colonel George W. Hughes to lead a survey party and pick a proposed Panama Railroad roadbed to Panama City. – Wikipedia

April 7, 1849
Panama RR chartered in New York – American Railway Times, Feb 15, 1855.

May 1850
First construction on Panama Railroad started.

Sept 20, 1850
U.S. Senator Stephen Douglas (April 23, 1813 – June 3, 1861) arranges a checkerboard compromise to create the first federal land grant railroads, the Illinois Central and the Mobile & Ohio, as part of the Land Grant Act of 1850.  Despite several attempts in the intervening years, this was the first railroad land grant to actually pass Congress since 1833.

Jan 25, 1851
Arrival of locomotive Elephant, first steam locomotive in far West, also Cony (Otis) steam shovel Steam Paddy, and 30 dump cars – Daily Alta California, Volume 2, Number 46, 25 January 1851.  Locomotive Elephant not allowed to operate in San Francisco streets, remains crated.

Aug 4, 1852
Sacramento Valley Railroad organized.

US Secretary of War Jefferson Davis dispatched six parties of US Army Topographical Engineers to survey potential routes for a Pacific Railroad.  Results were published in 1854 and 1855 in twelve massive volumes, plus additional volumes through 1858.

April 1854
Theodore D. Judah left New York for California to become Chief engineer of SVRR, traveling via steamer and overland via Nicaragua.

May 8, 1854
Judah arrived in Sacramento by steamer – Sacramento Daily Union, Volume 7, Number 974, 8 May 1854.

May 18, 1854
Judah began survey for Sac Valley RR – Sacramento Daily Union, Volume 7, Number 984, 19 May 1854.

Dec 15, 1854
Union Wharf and Plank Walk Company incorporated.  Built as a horse-powered railroad from the town of Union (later called Arcata) to the end of a wharf in Humboldt Bay.  Generally considered the first common carrier railroad (horse powered) in California.  Converted to steam in 1875.  Reorganized in 1881 as the Arcata & Mad River RR.

Jan 28, 1855
Panama Railroad completed.  1st railroad to connect the Atlantic (Caribbean) and the Pacific (Gulf of Panama).  First revenue train ran over the full length of the railroad on this date.  US built and owned.  From the Atlantic port it traveled southeast to reach the Pacific port, just as the Panama Canal does today.

Feb 12, 1855
Sac Valley official ground breaking; one contractor started Friday Feb 9 east of Sacramento – Sacramento Daily Union, Volume 8, Number 1213, 12 February 1855.  Grading of the Sacramento Valley RR started on the levee at Front and “L” streets in Sacramento.

Feb 16, 1855
Panama Railroad officially opened.

Aug 9, 1855
First rail laid on the Sacramento Valley RR.

Aug. 17, 1855
First Sacramento Valley RR locomotive fired up, first steam locomotive operated in the far West. – Sacramento Daily Union, Volume 9, Number 1372, 18 August 1855

Oct 3, 1855
Sac Valley 2nd loco arrival in Sacramento. – – Sacramento Daily Union, Volume 10, Number 1411, 3 October 1855.
Second loco unloaded on levee two days later. – Sacramento Daily Union, Volume 10, Number 1413, 5 October 1855.

Nov 10, 1855
Sac Valley third loco, CK Garrison, unloaded and placed on track in Sacramento. (Former Elephant, delivered to California in 1851 and never operated.) – Sacramento Daily Union, Volume 10, Number 1444, 10 November 1855.

Jan 22, 1856
Sacramento Valley RR track reached Negro Bar.

Feb 22, 1856
Sacramento Valley Railroad completed from Sacramento to Folsom and first train reached Folsom, distance 22.90 miles.

April 25, 1859
Ground broken for the Suez Canal.  At Port Said, Egypt, ground is broken for the Suez Canal, an artificial waterway intended to stretch 101 miles across the Isthmus of Suez and connect the Mediterranean and the Red seas. Ferdinand de Lesseps, the French diplomat who organized the colossal undertaking, delivered the pickax blow that inaugurated construction.

Aug 18, 1860
San Francisco & San Jose RR incorporated.

April 30, 1861
Central Pacific Articles of Association signed and Directors elected. (Sac Union 5-1-1861)

June 28, 1861
Central Pacific Rail Road Company of California Articles of Incorporation filed with Secretary of State in California.  To be the western link in the Transcontinental Railroad. (Farrar, SP Records; Sac Union 6-29-1861)

May 16, 1861
Ground broken and construction started on San Francisco & San Jose. (Farrar)

Aug 7, 1861
Judah survey to State line completed. (Sac Union Aug 7, 1861)

July 1, 1862
Pacific Railroad Act signed by President Abraham Lincoln and becomes law.  Officially recognized the Central Pacific as the Western part of the Transcontinental Railroad.  Union Pacific chartered by the act of Congress authorizing land grants and support for the Transcontinental Railroad. (National Archives; Library of Congress)

Sept 2, 1862
Union Pacific charter formally accepted by the Directors of the Union Pacific meeting in Chicago.  The acceptance was filed in the Department of the Interior June 26, 1863.

Jan 9, 1863
Central Pacific officially broke ground at Front Street near K Street in Sacramento with ceremony. (Farrar, SP records)

Oct 26, 1863
First rail of the Central Pacific laid at foot of I Street, without ceremony.

Oct 30, 1863
Union Pacific first Board of Directors meeting, organizes the company and elects officers.

Dec 2, 1863
Union Pacific broke ground in Omaha.

Jan 16, 1864
San Francisco & San Jose opened to freight and passenger traffic from Valencia Street, San Francisco, to San Jose. Extended to Bannon Street in February. (Farrar)

March 1864
Union Pacific grading started.

Aug 1864
First Union Pacific locomotive delivered in Omaha.

Oct 8, 1864
Amended Articles of Incorporation, changing name to Central Pacific Railroad Company of California. (Farrar, SP records)

July 10, 1865
First Union Pacific rail laid in Omaha.

Sept 10, 1865
California Pacific incorporated.  Initially conceived as a western link for the transcontinental railroad, connecting Sacramento with San Francisco via Vallejo, it later developed transcontinental aspirations of its own.

Dec 2, 1865
Southern Pacific RR filed articles of incorporation. (Marin Journal, Dec 16, 1865)

Western Pacific acquired by CP Associates from its owners.  The WP was organized by the interests controlling the San Francisco & San Jose.  (Not to be confused with the 20th century Western Pacific, a completely different company.)

March 1868
Control of San Francisco & San Jose acquired by the Southern Pacific, organized by the same owners as the SF&SJ.  Control of SP acquired by the CP Associates later that same year.

March 8, 1869
Union Pacific rails reach Ogden.

April 8, 1869
CP Huntington for Central Pacific and GM Dodge for Union Pacific meet in Washington DC and agree that the two lines should meet at “the summit of Promontory Point,” and that the permanent junction would be “within eight miles of Ogden.”

May 10, 1869
Central Pacific and Union Pacific joined at Promontory, Utah, in Golden Spike ceremony.  1st transcontinental railroad in US.

May 13, 1869
Regular service inaugurated between Sacramento and Omaha.  Connecting railroads provided service from the Atlantic.

Sept 8, 1869
Western Pacific completed and opened for service between Sacramento and Alameda.  A branch line from Niles connected in San Jose with the Southern Pacific (SF&SJ). Last Spike driven at the San Joaquin River crossing south of Stockton, and the first through train crossed the bridge on this date.

Nov 8, 1869
Central Pacific overland passenger terminus transferred from Alameda to Oakland, Cal.

Nov 17, 1869
Opening of the Suez Canal diverted most of the Oriental traffic that had been expected to pass over the Central and Union Pacific line.  High value, high speed tea and silk traffic continued to use the American transcontinental route to Europe into the 20th century.

Dec 6, 1869
First scheduled train to use Ogden as junction between CP and UP, instead of Promontory.

Feb 15, 1870
Ground broken for Northern Pacific Railway at Carlton near Duluth, Minn

May 31, 1870
Boston Board of Trade train arrived in San Francisco (running up the Southern Pacific – formerly the San Francisco & San Jose –  into the City).  1st true transcontinental train to run from the Atlantic coast to the Pacific coast of the US.

Apr 13, 1871
Peter Donahue sold the San Francisco & North Pacific to the California Pacific, who planned to move their terminal from Vallejo to Marin County, closer to San Francisco.

Aug 1, 1871
Control of the California Pacific acquired by Big Four, eliminating potential transcontinental competitor.  Transcontinental passenger traffic was diverted from the Western Pacific to this faster line to San Francisco via Vallejo and a long ferry ride.

Mar 1872
Union Pacific Eastern Division (Kansas Pacific opened the bridge across the Missouri River.  Kansas Pacific later absorbed by Union Pacific.

Jan 1873
After considering and rejecting moving the terminal of the transcontinental railroad from Oakland to Marin County, the Big Four sold the San Francisco & North Pacific (acquired with the California Pacific purchase) back to Peter Donahue.

March 25, 1873
Union Pacific Missouri River Bridge opened, directly connecting Council Bluffs, Iowa, with Omaha, Nebraska by rail, replacing the car ferry – and rails temporarily laid directly on ice in winter..

Sept 5, 1876
First through train from San Francisco reaches Los Angeles.

Nov 1879
Tripartite agreement in which the St Louis & San Francisco and the Atchison, Topeka & Santa Fe agree to jointly build the Atlantic & Pacific.

Dec 28, 1879
Train ferry Solano, largest in world, placed in service on the revised transcontinental route west of Sacramento, connecting the California Pacific line with Oakland ferry terminal.  Finally replaced by a bridge on Oct 14, 1930.

Oct 23, 1880
California Southern Railroad incorporated for the purpose of serving as the Pacific coast terminus for the Atlantic & Pacific and locating that terminus at San Diego.  Atchison, Topeka & Santa Fe President Thomas Nickerson named treasurer of California Southern, representing the official tie between the companies.  Actual terminus established at National City, where the terminal depot and general office building was constructed in 1882.

Mar 8, 1881
Connection between Southern Pacific and Atchison, Topeka & Santa Fe at Deming, N.M., forming second transcontinental route.  SP does not route traffic via Santa Fe.  Southern Pacific Southern Division trackage, in Southern California, Arizona and New Mexico, was leased to the Central Pacific for operation during this time period.

Dec 1, 1881
Central Pacific assumed operating control of Galveston, Harrisburg & San Antonio (GH&SA, known as the Sunset Route ).  Control returned to GH&SA’s own organization (CP owned) Feb 1, 1883, under new Texas state railroad laws.

Jan 1, 1882
Texas and Pacific met Southern Pacific at Sierra Blanca, Texas, forming another transcontinental connection.

Jan 1882
C.P. Huntington and Jay Gould together purchased a half interest in the St Louis & San Francisco (Frisco), which itself owned a half interest in the Atlantic & Pacific.  Huntington envisioned a true transcontinental line connecting his Chesapeake & Ohio system with the Central and Southern Pacific system via the Frisco and the Atlantic & Pacific.  In 1884 Huntington sold his interest in the Atlantic & Pacific to the Santa Fe as part of a larger settlement, and turned his attention to extending his Chesapeake & Ohio system to a Southern Pacific connection at New Orleans.

Oct 25, 1882
The Sonora Railway, built from the Arizona border to the port of Guaymas, Mexico, by the Atchison, Topeka & Santa Fe to provide a Pacific Coast outlet, was officially opened on this day.  It was less successful than hoped, leading the Santa Fe to place more emphasis on its Atlantic & Pacific line to California.  In 1898 the Sonora Railway was leased to the Southern Pacific as part of a larger exchange of trackage between that company and the Santa Fe.

About 1883
Central Pacific interests gained control of the Morgan Lines (Morgan’s Louisiana & Texas and Louisiana Western), providing access across Texas to New Orleans.

Jan 12, 1883
Last spike driven on Pecos River bridge, completing the Sunset Route, a through line from California to New Orleans, with associated steamer connections to New York.  Through service between San Francisco and New Orleans inaugurated Feb 7, 1883.  1st US route from the Atlantic (Gulf of Mexico) to the Pacific controlled by a single company (Central Pacific), arguably the first US transcontinental railroad company.

Feb 5, 1883
1st through passenger trains between Los Angeles and New Orleans leave their respective terminals.

May 21, 1883
Denver & Rio Grande and Denver & Rio Grande Western completed through narrow gauge line from Denver to a Central Pacific connection at Ogden, Utah.  Line subsequently standard gauged.

Aug 3, 1883
Atlantic & Pacific connection across the Colorado River completed at the Needles, meeting the Southern Pacific at the California border and forming another US transcontinental line.  Again, SP refused to develop traffic over this new connection.  Santa Fe subsequently purchased the Southern Pacific’s Mojave to Needles branch on Aug 20, 1884.

Sept 8, 1883
Northern Pacific completed with driving of gold spike at Gold Creek, Montana, forming, in conjunction with the Oregon Railway & Navigation Co., a transcontinental line from the Great Lakes to Portland, Oregon.

Oct 21, 1883
1st through passenger service via the Atlantic & Pacific and Southern Pacific.

Mar 17, 1884
Southern Pacific Company incorporated in Kentucky as a holding company for Associates (CP & SP) interests.  Southern Pacific Railroad leased on Mar 1, 1885 – also ML&T; Central Pacific Railroad leased on April 1, 1885.  Central Pacific name gradually disappeared over the next decades until finally extinguished in 1959.

Oct 1, 1884
Atlantic & Pacific assumes control of Southern Pacific line between Needles and Mojave and obtains trackage rights on SP from Mojave to San Francisco.

Nov 7, 1884
Atchison, Topeka & Santa Fe purchased full control of the California Southern, securing its outlet to the coast.

Nov 25, 1884
Oregon Railway & Navigation Co. (OR&N) and Oregon Short Line (Union Pacific controlled) joined at Huntington, Oregon, completing transcontinental link.  Union Pacific subsequently acquired control of OR&N, lost it, then under Harriman reacquired permanent control.

Nov 7, 1885
Canadian Pacific completed at Craigellachie, 1st Canadian transcontinental rail line.

Nov 14, 1885
First California Southern/Atlantic & Pacific/Atchison, Topeka & Santa Fe through transcontinental train departed for the East from the California Southern depot at National City.  The last spike actually connecting the California Southern to the Atlantic & Pacific was driven Nov 15.  On Nov 16 the first through transcontinental train from the East arrived at the National City depot.  Celebrations marking the completion were held in San Diego on Nov 18.  These events mark the true end of Central Pacific/Southern Pacific monopoly of California transcontinental rail transportation, and the start of a rate war between the two rail networks.

July 4, 1886
First scheduled Canadian Pacific transcontinental train arrived at western terminus, Port Moody, British Columbia.

May 12, 1887
Southern Pacific Company acquired control of Oregon & California, officially leased to SPCo on July 1, 1887.

May 23, 1887
First official train arrived at new Canadian Pacific terminal over extension from Port Moody to Vancouver.

Dec 17, 1887
Oregon & California last spike driven at Ashland, completing line between California and Portland, Oregon.

April 29, 1888
AT&SF affiliated CSF&C Kansas City to Chicago line opened after completion of Missouri River Bridge.

May 27, 1888
Northern Pacific completed line through the Cascades to Tacoma, Washington, ending its reliance on the Oregon Railway & Navigation Co. for a Pacific Coast terminal.

Union Pacific begins daily through service, Chicago-Portland and SF

Jan 5, 1893
Great Northern completed line to Puget Sound, the first transcontinental line built without federal land grant support.

July 29, 1899
Central Pacific Railroad reorganized as Central Pacific Railway as part of the restructuring to pay off the bond debt from construction days to the Federal Government.

Collis P. Huntington, last of the Big Four, died.

E. H. Harriman of the Union Pacific acquired control of the Southern Pacific.  The two railroads were operated together as the Associated Lines.  Union Pacific forced to divest its control of Southern Pacific in 1913 by government anti-trust action.

Jan 1, 1902
ML&T removed for SPCo lease and operated by its own company.

March 8, 1904
Lucin Cutoff opened across Great Salt Lake.

March 20, 1904
SP Coast Line completed.

Jan 20, 1905
San Pedro, Los Angeles & Salt Lake (Union Pacific affiliated) drove last spike in their line between Los Angeles and Utah.

May 14, 1909
Chicago, Milwaukee & St Paul completed to Seattle, the last US Pacific Northwest transcontinental line.

Nov 1, 1909
Western Pacific line between Oakland and Salt Lake City completed, the last US transcontinental railroad to reach completion.  Built by the Gould interests to secure a Pacific Coast outlet for the Rio Grande Western and other Gould lines, in response to the Harriman control of the Union Pacific, the Southern Pacific and the San Pedro, Los Angeles & Salt Lake.

April 9, 1914
Grand Trunk Pacific completed from Winnipeg to Prince Rupert, British Columbia, the 2nd Canadian transcontinental line.  Bankruptcy forced government takeover in May 1915 under the Canadian Government Railways, becoming the Canadian National in June 1919.

Canadian Northern completed from Montreal to Vancouver, British Columbia, the 3rd Canadian transcontinental line.  Bankruptcy forced government takeover in 1917, leading to formation of the Canadian National in June 1919.

Jan 1, 1926
Oregon & California property deeded to Southern Pacific Company; O&C corporation dissolved Jan 25, 1929.

Mar 1, 1927
All major Southern Pacific controlled lines in Texas and Louisiana leased to the Texas & New Orleans, and subsequently merged under T&NO on June 30, 1934.

Southern Pacific Company acquired control of the St Louis & Southwestern (Cotton Belt).

Sept 30, 1947
Southern Pacific Company reincorporated as a Delaware corporation after changes in the Kentucky corporation law.

Sept 30, 1955
Southern Pacific Railroad merged with Southern Pacific Company.

June 30, 1959
Central Pacific merged with Southern Pacific Company.

Nov 1, 1961
Texas & New Orleans merged with Southern Pacific Company.

Nov 26, 1969
Southern Pacific Company reorganized as Southern Pacific Transportation Company, itself a subsidiary of the newly formed Southern Pacific Company.

Union Pacific acquired the Western Pacific, and also the Missouri Pacific.

Dec 31, 1983
Southern Pacific Company (parent of Southern Pacific Transportation Company) and Santa Fe Industries (parent of Atchison Topeka & Santa Fe Railway) merged to form Santa Fe Southern Pacific Corporation.  Planned merger of the railroads denied by Interstate Commerce Commission (ICC) on final appeal June 30, 1987.

Oct 13, 1988
Rio Grande Industries, owners of the Denver & Rio Grande Western, took control of Southern Pacific Transportation Company following a Dec 28, 1987 purchase and subsequent ICC approval.

May 1, 1989
Southern Pacific Transportation Co. and Denver & Rio Grande Western Railroad combined their two operating departments under a single operation, known as Southern Pacific Lines

May 4, 1993
Rio Grande Industries changed its name to Southern Pacific Rail Corporation (SPRC).

Sept 11, 1996
Union Pacific purchases the Southern Pacific, unifying the original transcontinental partners, and reassembling Harriman’s Associated Lines on an even grander scale.  This functionally combines the turn-of-the-century Harriman Lines (UP and SP) and Gould Lines (MP, D&RGW, and WP), plus more.  In an interesting twist, the Southern Pacific corporate shell was found to be more advantageous, so Union Pacific was merged into Southern Pacific, and then the whole thing renamed Union Pacific.