“ Almost all people have, at one stage or another in their history felt and expressed the need to extend their territory and also to explain and justify their need both to the world and to themselves.” ( John A. Hawgood, Manifest Destiny, p126) When North America was first being colonised in the early 17th century, the settlers made their home along the coasts of the ocean and the shores of the nearby rivers. Nevertheless, as the population kept growing, adventurers, trappers and many mores, started to move west, farther from waterways and from the Atlantic coast. Early westward expansion began… However, it is in the first half of the 19th century that the United Sates gained most of its lands, sometimes buying them to their original owners, sometimes simply stealing them (There were actually 13 cases of land annexation during this century). We can thus wonder why the USA needed to enlarge its country so dramatically and will therefore analyse the reasons of this territorial expansion. Though it is clear that a large number of political reasons actually led to the annexation of a few western territories, we will rather concentrate on other main points. First of all, territorial expansion can be explained starting from two main reasons: the explosive population growth and the “restless individual energy of the people” (D.E. Fehrenbacher, The Era of Expansion, 1800-1848,(1969),p2). (Indeed, the rag-to-riches myth was very present in the settlers’ mind…). On the other hand, I believe that the desire of expansion was connected with military security, commercial reasons and with the growing sense of anxiety that Americans felt towards Great Britain. Finally, we have to bear in mind that the American territorial expansion was the physical response to the doctrine of “Manifest Destiny”. ***** ***** **** To begin with, America’s territorial expansion is a conse...