The First Transcontinental Railroad, completed May 10, 1869, linked the nation and significantly reduced cross-country travel time from months to less than a week. The Central Pacific Railroad, the company that built the western portion of the railroad, employed more than 10,000 Chinese laborers.
Learn more:
https://www.pbs.org/ancestorsintheamericas/time_17.html
https://www.nytimes.com/2019/05/14/us/california-today-chinese-railroad-workers.html