When tracks were laid for the new Southern Pacific Railroad, two teams raced to join each other, one moving south through the Central Valley and the other heading north from Los Angeles. Many geological obstacles along the route required innovative solutions, such as the circling Tehachapi Loop seen here.
After 1860, the railroad was a persistent subject in Carleton Watkins's photographs. As a close friend of Collis P. Huntington, one of the executives of the Central Pacific Railroad and its extension, the Southern Pacific, Watkins traveled along the railways for many years with complementary annual passes. He essentially functioned as an unofficial photographer of the railroads, often taking images on or near the new tracks.