Look at a map of the United States today. Much of the American Southwest became part of the country during the presidency of James K. Polk.
When Polk became America’s 11th president in 1845, the country was expanding westward. But major questions remained about territorial boundaries, relations with Mexico, and whether slavery would be allowed in new territories.
Polk wanted the United States to reach the Pacific Ocean.
During his presidency, the United States reached an agreement with Britain over the Oregon boundary. But relations with Mexico led to war in 1846.
The Mexican American War ended with the Treaty of Guadalupe Hidalgo in 1848.
Under that treaty, Mexico ceded a vast territory that included present day California, Nevada, Utah, and portions of several other states. The United States agreed to pay Mexico $15 million and assume certain claims by American citizens.
Polk achieved much of the territorial expansion he wanted.
But gaining land also created new problems.
Every new territory raised another difficult question: Would slavery be permitted there?
Those disagreements intensified the conflict between Northern and Southern states in the years leading to the Civil War.
Polk’s presidency helped create the geographic United States we recognize today. It also demonstrated that expanding a country could deepen disagreements about what kind of country it would become.
Sources
- National Archives: Treaty of Guadalupe Hidalgo (1848)
- U.S. Department of State: Texas Annexation, the Mexican American War, and the Treaty of Guadalupe Hidalgo
- Library of Congress: James K. Polk Papers