Several factors combined to produce the expansionist movement known as the Manifest Destiny. Chief among these was the seemingly habitual ambition, nurtured by the restlessness of the American pioneer spirit, to move on to new land.
             Expanding the United States to the Pacific involved risks, for it meant taking the land claimed or settled by other peoples. The United States, with limited military power, had to weigh carefully the possibility of hostilities with Native Americans on the plains, with Mexicoin Texas, and with Britain.
             The first area where the advance of American settlement caused serious friction with Britian was in the Northeast. Because of confusing language in the Treaty of Paris after the Revolution, the northern and eastern boundaries of Maine had been uncertain. As long as the region was unoccupied, this was not a serious matter. In 1838, however, the British decided to construct an overland road to connect St. John on the Bay of Fundy with Montreal and Quebec. In February 1839, settlers from Maine, pushing into the fertile Aroostook Valley, clashed with British workers who were felling trees for the road project. The struggle, fought mostly with fists, is known as the Aroostook War. It nearly led to something more serious when Maine and New Brunswick called out their militias, and congress authorized President Van Buren to call for 50,00 soldiers in case of war.
             In spite of friction and ill feeling, there were practical reasons for persuing peace. The most important reason was that the United States and Brtitain each profited from the other's trade. The negotiators--Daniel Webster, the American secretary of state, and Lord Ashburton, the husband of an Americanheiress--decided that it was impossible to fix the correct boundary of Maine. Instead, the 1842 treaty divided the disputed territory as fairly as they could. Great Britain got what it wanted most: enough land to make possible a dir...