Wider the Course of Empire Takes Its Way

In the first sentence of the first chapter of the only book he ever finished, Frederick Jackson Turner wrote, "The history of the United States is the history of a growing nation." These words were published in 1906, but the perspective that informed them endures. Even now the nation remains both the primary object and category of analysis in the writing of U.S. history. And yet Turner also hinted at a decidedly different story, proposing in the same chapter that "From one point of view the United States, even in this day of its youth, was more like an empire than a nation."¹ This interpretation has been much slower to stick; indeed, among the core tenets of American historical difference has been the assumption that the United States was never an imperial transgressor. Historians arguing otherwise have generally relied on caveats to do so: that American imperialism was ambivalent or accidental; that the United States was a benevolent empire of liberty; that America's was but a momentary empire. Of late, however, and spurred in part by the American invasion of Iraq in 2003, a growing number of historians have embraced the imperial point of view that Turner gestured toward. Looking out from the vantage of empire, they have begun to consider U.S. history anew, offering insights into the configurations and exercise of American power that have unsettled the nation's analytical priority.²

The imperial reassessment continues in the two books under review. Steven Hahn's A Nation Without Borders is a synthesis of American history during the long nineteenth century. Matthew Karp's This Vast Southern Empire is a monograph focused on proslavery foreign policymakers before the Civil War. Even as they operate on different scales of analysis, however, these studies both place empire at the center of nineteenth-century U.S. history.

Hahn's A Nation Without Borders, the third volume of the Penguin History of the United States, begins and ends not in the United States at all but in Mexico. This change of setting is indicative of the creativity that distinguishes Hahn's account, which opens amidst a wave of territorial disputes over northern Mexico in the 1830s and proceeds though the aftermath of Woodrow Wilson's decision to invade revolutionary Mexico in the 1910s. Along the way, Hahn offers less a survey than a radical retelling of U.S. history. He populates his account with much that is familiar—the Dred Scott case, Jane Addams, the Farmers' Alliance—and much that is likely to be less so—the Bear Flag Republic, William Webb, the Yaqui—all juxtaposed in surprising ways throughout twelve chapters.

Across its expansive sweep the overriding theme of Hahn's narrative is empire. To be sure, the subject of empire has not been absent from other recent syntheses of nineteenth-century U.S. history, most notably Daniel Walker Howe's What Hath God Wrought: The Transformation of America, 1815–1848 (2007). But empire here takes on a new importance; it becomes both an animating force and the underlying constant for the entirety of the period. During the first half of the nineteenth century, in Hahn's telling, the United States did not lack for imperial aspirations, as nonslaveholders concentrated in the Northeast and slaveholders based in the Mississippi Valley competed to extend their rival visions of empire from California to Kansas to Cuba. Following an innovative line of analysis, Hahn proceeds to show how this competition produced a crisis over slavery that was central to a more general conflict over sovereignty. The federal government, he argues, was unable to rein in the proslavery filibusters, Native Americans, and Mormons who populated territories ostensibly brought under its jurisdiction by way of imperial...