[wburg]

The Pacific Railroad (more commonly known as the Transcontinental Railroad, technically the Overland Route) was built by Central Pacific, starting from here, and Union Pacific, starting from Omaha, Nebraska. They met at Promontory Summit (not Promontory Point!) and UP technically had the eastern half.

Central Pacific was based out of Sacramento originally, but they moved their offices to San Francisco. The main shops were still located here. For a variety of legal reasons, Central Pacific purchased a company called "Southern Pacific," incorporated in Kentucky (for tax purposes), and used it as a holding company. Southern Pacific was pretty much the dominant economic and political force in California until around 1900.

SP had a line down to southern California, and their "Sunset Route" through the Southwest was actually more reliable than the Overland Route (less likely to get snowed in in winter.) Their first competitor in southern California was the Atchison Topeka & Santa Fe--Union Pacific didn't enter southern California until much later (maybe 1920s?)

Leland Stanford bought his mansion in Sacramento (it was already built when he moved in) and greatly expanded it after becoming governor and building the railroad. He later moved to San Francisco when CP/SP relocated its headquarters to San Francisco--but when the line was originally built, you couldn't stay on the train to San Francisco, you switched to riverboat at Sacramento.

The Crocker home/gallery wasn't built by Charles Crocker, who was one of the Big Four--it was built by his brother, E.B. Crocker, who was Central Pacific's principal attorney. Charles Crocker and C.P. Huntington built homes in San Francisco, along with Stanford. Mark Hopkins built a house in San Francisco at his wife's insistence. I think all four of the mansions they built in San Francisco were destroyed in the 1906 earthquake, so really the Stanford Mansion is the only home of the Big Four left.

None of them built homes in Stockton (and why would they?). Stockton wanted to be chosen by CP as the site for their division point, where traffic headed up the peninsula to San Francisco would depart their main line. However, Stockton didn't offer enough to CP for the privilege, so CP started their own town a few miles from Stockton to support the division yard, named after Leland Stanford's in-laws--the town of Lathrop is still there.