his article tells us the early conflicts, fears, vagueness and historical backgrounds over territorial expansion. The United States had been established with obscure concept of national boundaries. The constitution itself did not articulate geographic limit of the states, partly because the members of the constitutional convention were unsure of their territorial limit and expansion. So it says that the Louisiana Purchase- the first territorial addition to the original thirteen states, was the product of coincidence, misunderstanding, and good luck. Somehow, in the beginning, it was not urgent issue. But, things had to be changed regarding the creation of new states from acquisitions of national territory. Then it brought fears that westward expansion might bring disadvantage to the union rather than constructive progress, since early leaders were afraid of undesired diffusion of population and worried about dealing with status of people in new states. And moreover, in reality, the Louisiana Purchase seemed to lead to decrease in their economic profit. They hardly felt the immediate benefit out of territorial expansion despite the fact that the Mississippi River was important way for shipment. People against the idea of expansion were also afraid of the possibility of ruining their homogeneity by future immigrants along with acquisitions of non-Anglo- Saxon world. Conflicts between North and South also impede the idea of territorial expansion because of the chance of undesirably strengthening one side by territorial addition. In spite of all reasonable accounts, the states came to be more and more convinced by the idea of expansion that appeared to guarantee more progress and prosperity. In the mid-19th century, ??Dubious Destiny?? was transformed into ??Manifest Destiny??-which lead the U.S. to the expansion in the end.