The special relationship between the United Kingdom, an established and secure power, and the United States, a rising one, began after the War of 1812, as the former enemies sought accommodation with, rather than the annihilation of, one another. At the same time, Mexico, also a rising power, was not so fortunate. Its relationship with Spain, an established but declining power, turned hostile with Spain’s final exit from North America after Mexico’s War of Independence, leaving its former colony isolated, internally unstable, and vulnerable to external attack. Significantly, Mexico posed little threat to its northern neighbor. By the third decade of the eighteenth century, then, the fate of North America was largely discernable. Nevertheless, the three-century journey to get to this point had been anything but predictable. The United States’ rise as a regional power was very much conditioned by constantly shifting transcontinental, transpacific, and above all transatlantic factors, all of which influenced North America’s three interactive cultural spheres: the Indigenous, the Hispano, and the Anglo. And while the United States profoundly shaped the history of Canada and Mexico, so, too, did these two transcontinental countries likewise shape the course of U.S. history. In this ground-breaking work, Kevin Fernlund shows us that any society’s social development is directly related to its own social power and, just as crucially, to the protective extension or destructive intrusion of the social power of other societies.