Who was the U.S. president most associated with Manifest Destiny in the 1840s?

The U.S. president most associated with Manifest Destiny in the 1840s was James K. Polk. His presidency was closely tied to the belief that the United States was destined to expand across the North American continent.

Polk served as the 11th president from 1845 to 1849. During his administration, the United States annexed Texas in 1845, settled the Oregon boundary dispute with Britain in 1846, and fought the Mexican-American War from 1846 to 1848. The resulting Treaty of Guadalupe Hidalgo transferred a vast area—including present-day California, Nevada, Utah, and parts of several other states—to the United States.

Polk did not invent the phrase “Manifest Destiny”; journalist John L. O’Sullivan popularized it in 1845. However, Polk turned the expansionist idea into government policy more aggressively than any president of that era. Zachary Taylor succeeded him, while Andrew Jackson influenced Polk politically but was president during the preceding decade.