Final answer:
The Mexican-American War was criticized for potentially expanding slavery, threatening national unity, and disrupting the balance of free and slave states. It also caused political disenfranchisement and conflicts with the native populations. The war increased distrust in the U.S. by Latin America due to perceptions of American greed and aggression.
Step-by-step explanation:
Many Americans criticized the Mexican-American War for several reasons. They perceived the war as an aggressive expansion that threatened liberties and American values. Notably, historical figures such as John C. Calhoun and Abraham Lincoln opposed the war due to the rekindling of slavery debates which had been temporarily quelled by the gag rule. The war disrupted the balance of free and slave states established by the Missouri Compromise and threatened to throw the nation into a serious sectional crisis. Moreover, the subsequent westward expansion led to the displacement and disenfranchisement of Mexican populations in Texas and California. Conflicts with Native Americans also intensified, culminating in a series of violent encounters.
The idea of Manifest Destiny, closely associated with expansion, suggested that spreading the boundaries of the United States was equivalent to spreading freedom. However, this expansionism raised questions about the true nature of freedom, the role of the state, and ultimately was seen as a threat to national unity and security.
For Latin America, the war exacerbated negative sentiments towards the United States, with many believing that the conflict was instigated by American greed. This feeling led to increased distrust and long-lasting 'Yankeephobia' in Latin America. Overall, the repercussions of the Mexican-American War were deeply felt and sparked critical discussions about the American identity, the contradictions in its growth, and the ethical implications of its foreign policies.