On May 10, 1869, the 'Golden Spike' was driven at Promontory Summit, Utah, marking the completion of the first Transcontinental Railroad in the United States. The project connected the Central Pacific and Union Pacific railroads, linking the Atlantic and Pacific coasts by rail for the first time. Before the railroad, traveling across the continent took six months by wagon or weeks by sea around South America; the train reduced this journey to just one week. The construction was an immense engineering feat, largely built by the labor of Chinese and Irish immigrants who faced brutal conditions and discrimination. While the railroad accelerated economic growth and westward expansion, it had a devastating impact on Native American tribes, whose lands were seized and whose primary food source, the buffalo, was nearly hunted to extinction by the influx of settlers and hunters.