Workers from what Asian country make up more than 80% of the workforce that built the Central Pacific portion of the US transcontinental railroad?

The correct answer is China, as a significant majority of the workforce that constructed the Central Pacific portion of the US transcontinental railroad was composed of Chinese laborers. During the mid-19th century, specifically between the 1860s and 1870s, the Central Pacific Railroad Company actively recruited Chinese immigrants, who faced considerable hardships but contributed immensely to the project, especially in the Sierra Nevada mountains. Their labor was crucial in overcoming the challenging terrain and completing the railroad, which was vital for connecting the eastern and western United States.

The substantial representation of Chinese workers in this historical context underscores their essential role in America’s infrastructure development during that time. The other countries listed, such as Japan, Vietnam, and Burma, did not have comparable involvement in the transcontinental railroad's construction, making China the clear choice that accurately reflects the demographic makeup of the workforce during this monumental project.