Why did tensions rise between the American and and Mexicans?

Tensions between Americans and Mexicans rose primarily due to territorial disputes following the U.S. annexation of Texas in 1845, which Mexico still considered part of its territory. The U.S. desire for westward expansion, encapsulated in the idea of Manifest Destiny, further fueled conflicts over land and resources. Additionally, cultural differences, economic competition, and the U.S. military presence near the Mexican border exacerbated these tensions, ultimately leading to the outbreak of the Mexican-American War in 1846.