Why did some Americans oppose expansion overseas?

Some Americans opposed overseas expansion due to concerns about Imperialism and the moral implications of dominating other nations. Many believed it contradicted the core values of democracy and self-determination that the United States was founded upon. Additionally, there were fears that expansion would lead to increased conflict, both internationally and domestically, as well as potential economic burdens. Critics also worried about the treatment of newly acquired populations and the impact on American society and culture.