Question

in the 1850s, chinese immigrants established chinatowns in cities
mainly on the western coast of the united states.
mainly on the eastern coast of the united states
primarily in the midwestern united states.
primarily in the southern united states

Explanation:

In the 1850s, due to the California - Gold Rush and other economic opportunities, Chinese immigrants mainly settled on the western coast of the US and established Chinatowns there.

Answer:

A. mainly on the western coast of the United States