To the surprise of many, the new President proved to be his own man; he even ignored Jackson's wishes on several matters. Renouncing a second term for himself, he required the members of his cabinet, which included James Buchanan, Robert J. Walker, William L. Marcy, and Bancroft, to devote all their energies to their offices, not to campaigning to succeed him.
Polk announced that his administration would achieve "four great measures": reduction of the tariff; reestablishment of the independent treasury; settlement of the Oregon boundary dispute; and the acquisition of California. All were accomplished. The Walker Tariff, one of the lowest in U.S. history, was enacted in 1846, as was the bill restoring the Independent Treasury System. Despite the aggressive Democratic slogan "Fifty-four forty or fight," the dispute with Great Britain over Oregon was peaceably resolved with the adoption of lat. 49°N (the 49th parallel) as Oregon's northern boundary.
Relations with Mexico, on the other hand, reached a breaking point after the annexation of Texas. Polk had hoped to purchase California and to settle other difficulties with Mexico by negotiation. However, after the failure of the mission of John Slidell to Mexico, the President ordered the American advance to the Rio Grande that precipitated the Mexican War. As a result of the war, the United States acquired not only California but the entire Southwest.
Few presidents have worked harder, and few have equaled Polk's record of attaining specific, stated aims. He labored so strenuously in fact that his health gave way, and he died a few months after leaving office.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.