James K. Polk

1795 – 1849

James Knox Polk was the 11th president of the United States, serving from 1845 to 1849, and the principal architect of mid-19th-century American territorial expansion. He provoked the Mexican–American War of 1846 by sending U.S. troops into disputed border territory, and the subsequent treaty seized roughly half of Mexico's territory—including modern California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, and Wyoming—for the United States. The vast new lands also reignited the political fight over the expansion of slavery, helping to set the stage for the Civil War a generation later.

Last checked: May 10, 2026, 1:06 PM