On May 10, 1869, a ceremonial golden spike was driven at Promontory Summit in the Utah Territory, marking the completion of the first U.S. transcontinental railroad. The line connected the Central Pacific Railroad from the west with the Union Pacific Railroad from the east. This new link allowed travel between the Atlantic and Pacific coasts in days rather than weeks or months. It transformed commerce, migration, and communication across the continent. The project also relied on the labor of thousands of workers, including many Chinese immigrants, who faced harsh conditions and prejudice. The completion of the railroad stands as a major milestone in the physical unification of the United States.
