Final answer:
The transcontinental railroad could not have been built without the labor of Chinese and Irish immigrants.
Step-by-step explanation:
The transcontinental railroad could not have been built without the labor of thousands of workers. The primary groups of labor that were crucial to the construction of the railroad were Chinese immigrants and Irish immigrants. Chinese laborers, mostly from Guangdong province, were hired by the Central Pacific Railroad and played a vital role in building the western portion of the railroad, while Irish immigrants were predominantly employed by the Union Pacific Railroad to construct the eastern portion. These workers faced incredibly difficult conditions, including dangerous work environments, long hours, and low wages.
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