The company was purchased in September 1868 by a group of businessmen known as the Big Four: Charles Crocker, Leland Stanford, Mark Hopkins, Jr. and C. P. Huntington.

It extended from New Orleans through Texas to El Paso, across New Mexico and through Tucson, to Los Angeles, through most of California, including San Francisco and Sacramento.

Central Pacific lines extended east across Nevada to Ogden, Utah, and reached north through Oregon to Portland.

Ten years later, they moved into the historic 11-story, 65-metre (213 ft) Southern Pacific Building, also known as "The Landmark", located at One Market Street on the Embarcadero whose construction started in 1916.

[6][7] At its completion, the building's first floor was devoted to retail except for the portion facing the rear courtyard (opening to Mission Street), which was reserved for Southern Pacific.

[9] The SP was known for its mammoth back shops at Sacramento, California, which was one of the few in the country equipped to design and build locomotives on a large scale.

Sacramento was among the top ten largest shops in the US, occupying 200 acres of land with dozens of buildings and an average employment of 3,000, peaking at 7,000 during World War II.

The Alhambra Shops in Los Angeles consisted of 10 buildings and employed 1,500 but declined in importance when the Taylor Yard was built in 1930.

[11] Southern Pacific had a number of snow sheds in mountain terrain, and locomotive crews nearly asphyxiated from smoke in the cab.

Trains with names in italicized bold text still operate under Amtrak: The man or men who committed this horrible deed near Glendale may not be anarchists, technically speaking.

If the typical anarchist conceived that a railroad corporation should be terrorized, he would not scruple to wreck a passenger train and send scores and hundreds to instant death.

Among the more notable equipment is:On August 19, 2006, UP unveiled a brand new EMD SD70ACe locomotive, Union Pacific 1996, as part of a new heritage program.