The Central Pacific Railroad was a key part of the first transcontinental railroad in the United States, completed in 1869. It began construction in Sacramento, California and extended eastward, connecting with the Union Pacific Railroad at Promontory Summit, Utah. This project significantly improved transportation and commerce across the country. The railroad was built primarily by Chinese laborers, who played a crucial role in overcoming the challenging terrain of the Sierra Nevada mountains. The completion of the Central Pacific Railroad marked a major milestone in American history, facilitating westward expansion and contributing to the economic growth of the nation.