Why did congress pass laws banning some groups of immigrants and not others?

Congress passed laws banning certain groups of immigrants primarily due to economic, social, and political factors, often influenced by prevailing nativist sentiments. Legislation like the Chinese Exclusion Act of 1882 targeted specific ethnic groups perceived as threats to American jobs or societal norms. Additionally, these laws reflected racial and cultural biases, with some groups being deemed "undesirable" based on stereotypes or fears of competition. Such discriminatory practices were often justified by the belief that certain immigrants could not assimilate into American society.