USA HISTORY

Detailed explanation-1: -Polk ran on an expansionist platform where his main promises consisted of the annexation of Texas and the Oregon Territory.

Detailed explanation-2: -Under James Knox Polk, the United States grew by more than a million square miles, adding territory that now composes the states of Arizona, Utah, Nevada, California, Oregon, Idaho, Washington, much of New Mexico, and portions of Wyoming, Montana, and Colorado.

Detailed explanation-3: -Democrats replied Polk was the candidate who stood for expansion. He linked the Texas issue, popular in the South, with the Oregon question, attractive to the North. Polk also favored acquiring California. Even before he could take office, Congress passed a joint resolution offering annexation to Texas.

Detailed explanation-4: -Polk is chiefly known for extending the territory of the United States through the Mexican–American War; during his presidency, the United States expanded significantly with the annexation of the Republic of Texas, the Oregon Territory, and the Mexican Cession following American victory in the Mexican–American War.