Shoshone men and women in the Wyoming Territory. Note the white man in the bowler hat on the left side of the photo.
Union Pacific rolling mill workers:
Theodore Judah, engineer, surveyor, and father of the Central Pacific:
Thomas "Doc" Durant at the Union Pacific's end of track:
Construction work along the Union Pacific in 1868:
This is a link to an advertisement for the opening of the line to the Pacific. Note the travel time from Omaha to San Francisco.
Original stereograph image of the Cape Horn grade on the Central Pacific line:
Collis Huntington, the Sacramento merchant and Central Pacific Associate who brought the other big investors to the CP:
The Central Pacific Railroad Photographic Museum site maintains a page with several photos from the ceremony marking the completion of the transcontinental railroad in 1869. There are also scans of a few contemporary newspaper chronicles of the event.