How should one judge the policies and actions of the Polk administration? In order to arrive at a fair appraisal, one must first weigh the merits and demerits of its greatest accomplishment, the territorial annexations, around which nearly all its other actions revolved. The Polk administration added to the United States about 1.2 million square miles of territory—far more than any other administration before or since—and the enormous value of this territory was at once established by the discovery of gold in California. The victories of the Mexican War won the grudging but genuine respect of Europe. Britain withdrew most of its political influence from Mexico and a few years later, in the Clayton-Bulwer Treaty, agreed to share influence in Central America. The broad frontage on the western coast eventually made the United States a force in Pacific affairs. In effect, the United States was promoted to a second-rank power whose views must be consulted in all international questions relating to the northern half of the New World.
Within the United States the effects of the war and the annexations were more mixed. Like all wars this one cost money, which the prosperous United States could well spare, and lives, which families and friends could not. On the one hand, the war's heroics, superimposed on a rising Romantic movement in popular literature, refurbished American history back to the Revolution and renewed Americans' devotion to their old ideals, which had become a little tarnished. On the other hand, the victories created a spirit of "lick all creation," an overblown chauvinism with strong hints of militarism and racism that coarsened democratic sensibilities and laid American ideologies open to charges of hypocrisy. Europeans, especially conservatives, had long thought American institutions tainted with braggadocio; during the 1850s the whiff thickened to a stench. To Latin Americans, the events of 1843–1848 revealed perhaps for the first time the aggressive potential of their expanding neighbor, and a stereotype began to take shape in Latin American writing about the United States—the Colossus of the North.
But the most alarming effects of western annexations and the Mexican War were felt in American sectionalism, already a threat. By the early 1840s many Whigs had come to believe that further expansion in any direction would place intolerable strains on national unity. To abolitionists, Texas became a moral issue, what Charles Sumner called "our own original sin." Although abolitionists were partly reassured by the apparent evenhandedness of the Democratic party program of 1844 and Polk's inaugural address, the Oregon compromise at 49° struck them as a betrayal by the South and a southern president. When a seemingly unending war for limitless southern annexations followed, this northern sense of betrayal crystallized in the Wilmot Proviso (first introduced by one of Polk's own Democrats), which completed the association of slavery and expansion. The intense opposition to the war, partly Whig and partly antislavery, made it seem not only disruptive, setting one section against another, but sinful. "When the foreign war ends, the domestic war will begin ," warned the New York Gazette and Times in 1847. Ralph Waldo Emerson wrote in his journal that the war was a dose of arsenic, and he might well have applied the term to the acquisition of Texas and Oregon, too.
Given the mixed effects of the Polk administration's accomplishments, we may proceed to a few conclusions about Polk's own nature and methods. In the first place, it seems clear that he placed too great reliance on bold talk and too little confidence in the possibility of compromise. Suspicious by nature, he was inclined to view each offer by his opponents as a trap or an attempt to exploit American amiability and weakness. Although anxious to negotiate from an appearance of strength, he did not seem to think it necessary to build up the army and navy. As a result, he slipped into the dangerous practice of bluffing, not realizing or perhaps not caring how little respect American military forces inspired abroad. He probably counted on distance, trade, and the vulnerability of Canada to deter Britain from action and probably despised the Mexicans as too weak and disorganized to carry out their braggart threats.
Second, beyond these basic attitudes, much of Polk's foreign policy was improvised from month to month in response to events. The statement on Oregon in his inaugural address was a pacifier for the West; Buchanan's offer to Britain, an attempt to draw the fangs of British critics; and the withdrawal of that offer, a startled and indignant reflex. Meanwhile, Polk sought to renew diplomatic relations with Mexico in the hope of keeping peace during the annexation of Texas; but as soon as he understood Mexican weakness and confusion, he advanced his goal to the purchase of California. During his first year in office, he regarded war with either adversary as unlikely, but in March and April 1846, changed circumstances, especially political divisions at home, led him to favor a short tactical war with Mexico. As that war lengthened, he made other political and military decisions in reaction to events.
Third, Polk's largely improvised policies suffered from the phenomenon that twentieth-century analysts have called "escalation." This is a process by which an initial set of decisions starts a chain of causes and effects each more difficult to control than its predecessor, each widening the area of action and requiring increased forces and money. On inauguration day Polk had a fairly wide range of acceptable policies from which to choose. Some of his early actions and the pressure of circumstances gradually reduced this range. Eventually, after Scott had captured Mexico City, Polk found himself boxed in, unable to move, for ultraexpansionists at home would not let him withdraw from central Mexico to a tenable defensive line and he lacked the resources or the desire to extend the conquest over the whole country. Inaction, too, posed grave problems, for a few small guerrilla victories might have revived the Mexicans' morale and enabled them to cut Scott's long supply lines and isolate him in Mexico City. Fortunately, the disobedient Trist seized the fleeting moment of Mexican willingness to negotiate and so rescued the president from his dilemma.
Fourth, Polk failed to understand the deadly combination of the slavery and expansion issues until the explosive results were beyond his control. To this unfortunate outcome both his habit of improvisation and the element of escalation contributed. Before he became president, he shared the convictions of many southerners about slavery—that it was a practical necessity, though in many respects deplorable, and that it was a local matter and so should have no connection with national politics or international diplomacy. The ominous interjection of slavery into the Texas question during 1843 and 1844 seems to have made little impression on him.
Consequently, when the antislavery bloc opposed the war as a slaveholders' plot and seized upon the Wilmot Proviso as a weapon, Polk reacted with irritation at its using a potentially divisive issue for partisan purposes. As soon as it was clear that the proviso could not be shunted aside, he called in its sponsor, Representative David Wilmot, to assure him that in seeking territory from Mexico, he had no intention of extending slavery, for the land was unsuited to it, and that since no slave-state senator could vote for the proviso, its inclusion would defeat necessary war legislation and prolong hostilities indefinitely. As he told Representative Preston King, slavery had "no legitimate connection" with either the war or the peace treaty. Despite the accusations of abolitionists and some early historians, these assurances seem to have accurately represented his views.
Polk managed to end the war without reference to slavery, but the argument continued to simmer, and through 1848 the proviso was attached to every bill for the organization of government in the annexed territories. By now Polk was thoroughly alarmed that the issue might split not only the Democratic party but the country. After accepting the proviso in the Oregon territorial bill, he made it clear that he would agree to any compromise terms that the North proposed for the other territories: settlement of the slavery issue by the inhabitants, extension of the Missouri Compromise line to the Pacific, or submission of the whole matter to a judicial tribunal. Eventually he even favored immediate admission of California as a state without conditions attached (which would virtually guarantee the outlawry of slavery). In his last annual message to Congress he delivered an eloquent plea for tolerance and compromise in the name of "the glorious Union." He spent his final weeks in office making desperate but vain efforts to work out an acceptable formula.
All in all, one is forced to conclude that Polk's policies were much more hazardous than he realized, thanks to his overbold improvising, the phenomenon of escalation, the small forces that the United States deployed in the field, and the likelihood of deep divisions within the American parties, government, and people. Even assuming that Britain had no desire to fight its best customer, Polk could not be certain that a sense of honor over some uncontrollable local conflict in Oregon would not precipitate a general Anglo-American war. Britain had significant economic interests in Mexico, so a Mexican victory over Taylor on the Rio Grande would have facilitated a private loan from British bankers, and a military stalemate in northern or central Mexico would probably have led to British mediation, which rising American opposition to the war might have forced Polk to accept. An indefinite occupation of Mexico City and smoldering guerrilla warfare lasting through the American election of 1848 might well have caused an open break between ultraexpansionists largely supported by the South and pacifists backed by abolitionists.
Without placing too much weight on "contingent history," it is possible to imagine what might have happened had Polk made a different set of choices. An arguable alternative to bold tactics against either Britain or Mexico was the policy that Calhoun had recommended for Oregon—"masterly inactivity." This policy rested on two assumptions: the continuous, irresistible force of American western migration and Europe's customary involvement in Old World affairs. At Polk's inauguration, he might have refused direct comment on Oregon while examining the possibilities of a negotiated settlement with Britain and completing the annexation of Texas. If he had resisted the impulse to break off discussion with Pakenham, he might have had an agreement to announce in his first annual message, forestalling western resentment with a fait accompli. Failing that, he could have used western resentment to put pressure on Britain but without relinquishing the Oregon question to Congress.
In any case, Polk should have avoided an open break with Mexico before the Oregon controversy was completely settled. There was no need for haste; stationing Taylor at Corpus Christi would have protected Texas settlements adequately with a minimum of provocation to Mexico. As for California, careful analysis of British policy in Europe and in Texas should have reassured Polk that Britain had few designs on the Pacific coast outside of Oregon, where honor was involved. Why not allow American settlers to occupy California, keep American warships cruising off the coast, and see whether the Californians might not repeat the history of Texas? During some later European crisis (such as the revolutions of 1848 or the Crimean War of the mid-1850s), the United States would have been free to open negotiations with an independent California government, which by then might have observed the prosperity of Oregon under American rule.
Perhaps war with Mexico might have been avoided altogether. At worst, it would have been postponed until a more favorable moment, and with the United States already occupying Texas and California, any fighting would have been defensive and limited to border areas. Mexicans, of course, would have resented the loss of California under any circumstances, but they had no means of retaining it, and this course would have spared them the humiliation of a foreign army in their capital. Most important to the United States, a policy of more gradual, peaceful expansion would undoubtedly have avoided many of the bitter debates in Congress and the press that widened the alarming gap between North and South.
Such an alternative set of policies and actions might have won the United States less territory than was gained through war, for modern New Mexico and Arizona might have stayed with Mexico. Also these policies and actions would have required a president who combined Polk's determination, persistence, and knowledge of political machinery with greater sophistication in international affairs, a deeper conviction of the dangers of sectional strife, and greater charismatic appeal to the public, which he would have to carry with him at several crucial points. It would have required him to serve a second term or at least to influence the succession enough to ensure some continuity of policy. Perhaps this was impossible in the party politics of the 1840s. Perhaps also the divisiveness of the Texas issue had pushed the slavery question past the point of no return, as some historians have argued, placing it beyond the influence of rational argument and delaying tactics. In any case, the outline of an unexplored gradualist policy is useful in appraising the actual achievements of the Polk administration.
As in the case of many other presidents, the end of the Polk administration has an element of pathos. While trying in vain to settle the question of government in California and New Mexico, Polk prepared with quiet dignity to wind up his affairs and transfer power to his Whig successor. When General Taylor arrived in Washington to take over from his old commander, there was a day of embarrassed hesitation in the White House, lest Taylor fail to make the prescribed first social call on the sitting president. The inaugural ceremonies over, Polk and his wife left at once for their home in Tennessee, traveling by train and boat through much of the South. The warm welcome he received everywhere was tempered by an onset of his old illness, intensified by fear of cholera as he hurried through disease-ridden New Orleans and up the Mississippi. Arriving in Tennessee, haggard, coughing, and racked with diarrhea, he nevertheless made a round of visits with friends and relatives before settling down in a newly acquired home. In his last diary entry, on 2 June, he told of taking a carriage ride and unpacking books for arrangement in new shelves. Two weeks later, on 15 June 1849, he died.