What was one of the consequences of the annexation of Texas?

One significant consequence of the annexation of Texas in 1845 was the escalation of tensions between the United States and Mexico, ultimately leading to the Mexican-American War (1846-1848). Mexico viewed the annexation as an act of aggression, as it had not recognized Texas's independence from Mexican rule. This conflict resulted in significant territorial gains for the United States, including present-day California, Arizona, New Mexico, and more, but also deepened divisions over slavery in the expanding nation.