Who was the U.S. President during the Mexican-American War?

The U.S. President during the Mexican-American War was James K. Polk. He served from 1845 to 1849, a period characterized by significant territorial expansion for the United States. Polk was a strong proponent of Manifest Destiny, the belief that the U.S. was destined to expand across the North American continent. His administration was marked by the acquisition of vast territories, including California and New Mexico, which were integral parts of the conflict with Mexico. The war officially began in 1846 and was driven by disputes over territory, particularly following the annexation of Texas. Polk's leadership and his pursuit of expansionist policies were directly linked to the war's initiation and outcome, making him a pivotal figure in this historical context.