Answer: Manifest Destiny was a belief held by many Americans in the mid-1800s that it was their fate to expand and increase the territory of the United States from the Atlantic Ocean to the Pacific Ocean. President James K. Polk acted on this belief by annexing Texas and pushing for the Mexican-American War, which resulted in the Mexican Cession and the acquisition of California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, and Wyoming. The Gadsden Purchase was later made to acquire additional land in the southwest. The slogan "54 40 or Fight" was used to promote expansion northward into Oregon. However, the issue of slavery in the new territories led to increasing tensions between the North and South. Despite these challenges, the United States achieved Manifest Destiny by aggressively pursuing its expansionist goals through a combination of diplomacy and military force.
Step-by-step explanation: