James K. Polk
Legacy and historical view

Polk's historic reputation was initially formed by the attacks made on him in his own time. Whig politicians claimed that he was drawn from well-deserved obscurity. Sam Houston is said to have observed that Polk, a teetotaler, was "a victim of the use of water as a beverage". Little was published about him but two biographies released in the wake of his death. Polk was not again the subject of a major biography until 1922 when Eugene I. McCormac published James K. Polk: A Political Biography. McCormac relied heavily on Polk's presidential diary, first published in 1909. When historians began ranking the presidents in 1948, Polk ranked tenth in Arthur M. Schlesinger Sr. 's poll, and has subsequently ranked eighth in Schlesinger's 1962 poll, ninth in Arthur M. Schlesinger Jr. 's 1996 poll, and 14th in the 2017 survey by C-SPAN.

James Polk is today widely seen as a successful president; he is regarded as a man of destiny and a political chess master, who, through extraordinary diligence, worked to promote American democracy. Borneman deemed Polk the most effective president prior to the Civil War and noted that Polk expanded the power of the presidency, especially in its power as commander in chief and its oversight over the Executive Branch. Steven G. Calabresi and Christopher S. Yoo, in their history of presidential power, praised Polk's conduct of the Mexican War, "it seems unquestionable that his management of state affairs during this conflict was one of the strongest examples since Jackson of the use of presidential power to direct specifically the conduct of subordinate officers."

Historian John C. Pinheiro, analyzing Polk's impact and legacy, wrote that:

Polk accomplished nearly everything that he said he wanted to accomplish as President and everything he had promised in his party's platform: acquisition of the Oregon Territory, California, and the Territory of New Mexico; the positive settlement of the Texas border dispute; lower tariff rates; the establishment of a new federal depository system; and the strengthening of the executive office. He masterfully kept open lines of communication with Congress, established the Department of the Interior, built up an administrative press, and conducted himself as a representative of the whole people. Polk came into the presidency with a focused political agenda and a clear set of convictions. He left office the most successful President since George Washington in the accomplishment of his goals.

Bergeron noted that the matters that Polk settled, he settled for his time. The questions of the banking system, and of the tariff, which Polk had made two of the main issues of his presidency, were not significantly revised until the 1860s. Similarly, the Gadsden Purchase, and that of Alaska (1867), were the only major U.S. expansions until the 1890s.

Paul H. Bergeron wrote in his study of Polk's presidency: "Virtually everyone remembers Polk and his expansionist successes. He produced a new map of the United States, which fulfilled a continent-wide vision." "To look at that map," Robert W. Merry concluded, "and to take in the western and southwestern expanse included in it, is to see the magnitude of Polk's presidential accomplishments." Amy Greenberg, in her history of the Mexican War, found Polk's legacy to be more than territorial, "during a single brilliant term, he accomplished a feat that earlier presidents would have considered impossible. With the help of his wife, Sarah, he masterminded, provoked and successfully prosecuted a war that turned the United States into a world power." Borneman noted that in securing this expansion, Polk did not consider the likely effect on Mexicans and Native Americans, "That ignorance may well be debated on moral grounds, but it cannot take away Polk's stunning political achievement." James A. Rawley wrote in his American National Biography piece on Polk, "he added extensive territory to the United States, including Upper California and its valuable ports, and bequeathed a legacy of a nation poised on the Pacific rim prepared to emerge as a superpower in future generations".

To the retrospective eye of the historian Polk's alarums and excursions present an astonishing spectacle. Impelled by his conviction that successful diplomacy could rest only on a threat of force, he made his way, step by step, down the path to war. Then, viewing the war as a mere extension of his diplomatic scheme, he proceeded as confidently as a sleepwalker through a maze of obstacles and hazards to the peace settlement he had intended from the beginning.

David M. Pletcher

Historians have criticized Polk for not perceiving that his territorial gains set the table for civil war. Pletcher stated that Polk, like others of his time, failed "to understand that sectionalism and expansion had formed a new, explosive compound". Fred I. Greenstein, in his journal article on Polk, noted that Polk "lacked a far-seeing awareness of the problems that were bound to arise over the status of slavery in the territory acquired from Mexico" William Dusinberre, in his volume on Polk as slave owner, suggested "that Polk's deep personal involvement in the plantation slavery system... colored his stance on slavery-related issues".

Greenberg noted that Polk's war served as the training ground for that later conflict:

The conflict Polk engineered became the transformative event of the era. It not only changed the nation but also created a new generation of leaders, for good and for ill. In the military, Robert E. Lee, Ulysses S. Grant, Stonewall Jackson, George Meade, and Jefferson Davis all first experienced military command in Mexico. It was there that they learned the basis of the strategy and tactics that dominated the Civil War.
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