Rocklin's history is closely tied to the transcontinental railroad. In 1862, the Pacific Railroad Act granted the Central Pacific Railroad land near Secret Ravine. In 1864, the Central Pacific Railroad completed an extension of its track southwest from Newcastle to Secret Ravine. It named the area Rocklin after its granite quarry, and used the site as a refueling and water stop. The Central Pacific built a roundhouse in 1867. The transcontinental railroad was completed in 1869, significantly increasing railroad traffic through the town. According to the 1870 census, Rocklin had grown to 542 residents, and the majority of Irish immigrants had foregone mining and were working for the railroad. In 1908, the Central Pacific moved its facility from Rocklin to Roseville, where more land was available for expansion. The site in Roseville has remained in continuous use since. As of August 2014, it is the largest rail facility near the US West Coast.