Which is the best description of the historical impact of james k. polk's presidency?

The best description of the historical impact of James K. Polk's presidency would have to that he expanded the United States to the Pacific Ocean.  As the 11th president, Polk believed in manifest destiny, a popular idea in the United States during the 1800s.  Polk and others like him believed that the country should expand its boundaries to the Pacific Ocean, and that this was our nation's fate.  Early during his presidency, Polk annexed Texas in 1845 and made Oregon part of the United States in 1846.  After this, Polk was determined to gain California and New Mexico territories from Mexico to guarantee clear passage to the Pacific Ocean.  Polk saw California and New Mexico as rightfully belonging to the United States.  After provoking a war with Mexico in 1846, the United States gained the Mexican Cession in 1848.  The Mexican Cession relinquished the provinces of California and New Mexico to the United States in exchange for $15 million dollars.  The continental United States was nearly complete at the end of Polk's single term in office, which is his primary legacy.  

The answer would be a