Final answer:
Nativists in the West supported the federal law to restrict immigration and protect the interests of native-born Americans.
Step-by-step explanation:
The Nativists in the West supported the federal law depicted in the question because they sought to restrict immigration and protect the interests of native-born Americans. They aimed to prevent the migration of nonwhites, non-Protestants, Jews, and other 'new' immigrants from Central and Southern Europe. They believed in a vision of a white, Anglo-Saxon, and Protestant America, and wanted to limit the entry of individuals who did not align with this vision.