Caption reads: "Mark Hopkins who ran the day-to-day affairs of the Central Pacific, western link of the first transcontinental railroad."

Caption continues: "This photograph shows the grade being cut above Auburn. Please credit: Souther[n] Pacific Company. From: Association of American Railroads, Washington, D.C."

Caption reads: "A Central Pacific work train at Emigrant Gap, looking toward the East with the Yuba Mountains in the background. The horse and buggy mounted piggyback style on one of the flatcars may be those of Alfred A. Hart, pioneer Central Pacific photographer, who took this photo in 1868. Southern Pacific Photo X 3005."

Caption reads: "The flag marks the point where the Union Pacific and Central Pacific lines were joined on May 10, 1869. This photograph was taken two months later. Please credit: Union Pacific Railroad. From: Association of American Railroads, Washington, D.C."

Caption continues: "…is shown on the 'Big Trestle' which spanned a 405-foot ravine immediately east of the Golden Spike site at Promontory. The trestle was used for only a short time, soon abandoned in favor of a dirt-fill. UP photo by A.J. Russell. Courtesy Utah Historical Society."

Caption continues: "Note the small horse-drawn cars used to haul dirt"

Caption continues: "…meets Governor Leland Stanford's special train at Monument Point, near Promontory, Utah, where the governor was to participate in the 'Last Spike' ceremonies on May 10, 1869. Please credit: Southern Pacific Railroad. From: Association of American Railroads, Transportation Building, Washington, D.C. Note 'Jupiter' engine"

Credit: Union Pacific Railroad, From: Association of American Railroads, Transportation Building, Washington, D.C.

Caption: "The tremendous difficulties encountered by the Central Pacific Railroad in constructing the western end of a road to connect with the Union Pacific from the east are shown in this sketch by Joseph Becker. In the Sierra Nevada mountains, the Chinese coolies employed by the Central Pacific fought winter snows that drifted as high as 50 to 100 feet above the roadbed. From: Association of American Railroads, Transportation Building, Washington, D.C."

Caption: "The locomotive C.P. Huntington, CP engine No. 3 and one of the two smallest locomotives owned by the railroad, on Cape Horn high above the American River Canyon in 1867. This locomotive was donated to the State of California and is now at the California Exposition grounds in Sacramento. Southern Pacific Photo X281."