Since its inception, the heart of the United States has been burned by the burning desire to transcend its borders and establish itself as a world power, acquiring much of its territory during the 19th and early twentieth century. However, the means by which the United States acquired new territory changed dramatically in nature, moving from its original non-aggressive attitude to a largely assertive and bellicose temperament in the second half of its expansive conquest. To fully illustrate the changes in the motivations and character of US expansionism, the proliferation of border extension must be broken down into two separate time periods: land acquisition in the 18th and 19th centuries, motivated solely by the need to building and building founding a country, and the imperialist expansion of the late 19th and early 20th centuries, fueled by the desire to transform the United States into a world power. As the United States has evolved economically, religiously, and politically, its methods of expansionism have evolved from being mostly non-invasive to democratically controlled, all the while struggling to maintain a common goal and remain faithful to the ideals of his ancestors. To acquire new territories, the United States adopted methods of expansionism and later imperialism in the first and second phases of its expansion, respectively. These two means of self-affirmation had several striking similarities to each other. Through the expansionism of the 18th and 19th centuries, the main rationale behind annexation was for the country to grow and establish itself on its continent. Of course, the desire for greater political power in the new states has led to conflicts such as Bleed...... middle of paper ...... may be alien to American values. On paper, it was now legal for the United States to forcibly apply American traditions to newly annexed foreign citizens, on the grounds that their lives would be improved by such imperialistic control over their own customs. The culmination of the evolution of the United States from honest expansion to dominant imperialism is marked at the beginning of the 20th century. Despite attempting to stick to its core ideas and grow as a country itself, rapidly growing competition around the world has led to America's rather reluctant expulsion from continental expansion into global imperialism. Although it never strayed too far from its unconditional adherence to its faith, the United States was eventually forced to impose itself on the globe, thus marking it both as a powerful global ally to some and a global threat to others..