The American expansionist movement did not begin with Manifest Destiny and the push westward in the 1840s. Americans had been pushing boundaries since the colonial era, most notably across the Appalachian Mountains. Jefferson set the stage for expansionism with the Louisiana Purchase; the movement grew in the 1830s with the Indian Removal program under Jackson, “freeing” land east of the Mississippi for the expanding population. At the turn of the century, the overwhelming majority lived east of the Appalachian Mountains; just fifty years later, about half of all Americans lived west of the mountains, a tremendous demographic shift. 574 (Links to an external site.)
The rapid western expansion of the 1840s resulted in great part from demographic, economic, and political pressures. The population of the United States grew rapidly in the period from 1800-1850, rocketing from about five million to over twenty million in a fifty-year period. 575 (Links to an external site.) Americans were increasingly land-hungry as populations grew. Throughout many of the overworked farms of the east, soil fertility was declining, making the cheap land of the west more and more attractive. Politically, many feared that if the United States did not occupy the West, then the British would. Some reasoned that westward expansion would counterbalance the increasingly industrialized and urbanized northeast, assuring that the republic of the United States would continue to be rooted in the ideals and values of Jefferson’s yeoman farmer. Expansion deeply influenced U.S. foreign policy; to the south, tensions arose with Mexico as thousands of Americans immigrated into the Mexican state of Coahuila y Tejas, hereafter referred to as Texas. Expansion was also deeply economically motivated. For example, Eastern merchants wanted control of west coast ports to trade with Asia. Overall, many Americans envisioned the same end, even though they favored expansion for different reasons; many, however, came to equate the idea of “spreading freedom” with spreading the United States .