( Henry J. Sage 1996-2003 internet http://www.nv.cc.va.us) .
The United States first began to work within it's own borders. Pushing natives into marginal lands and reservations, the American elite were beginning to resemble some of that European imperialistic influence. In the early 1800's, President Monroe took a giant step towards using the main land to the county's advantage. Establishing the Monroe Doctrine, President Monroe, " claimed the Americas as a U.S. protectorate, and his proclamation served as a justification for U.S. intervention in hemispheric affairs. Until the late nineteenth century, the United States mostly exercised informal influence in the Americas and sought to guarantee free trade in the region." (Bentley Traditions pg. 952) The land expansions made by U.S. leaders allowed for the nation's entrepreneurs to market the country's raw materials in world trade. By gaining free trade throughout the land, American businessmen began to understand the benefits of imperialism.
Going beyond the mainland, U.S. leaders decided to look around to see if they could acquire any more territories. The United States sought an overseas empire during this period probably because several European nations (Germany, the Netherlands, Great Britain, France Portugal & Belgium) had already begun carving up much of African and Asia for themselves. These countries were not interested in settling in these lands. In fact, the U.S.'s aim of imperialism was to declare political and economic control over foreign territories in order to gain new markets, have access to their resources for trade, and enjoy strategic military advantages. Once the United States emerged from the Civil War, many were anxious to catch up with the European powers.
In 1867, the U.S. purchased Alaska from Russia, because it provided the main entrance into western Canada. In addition, at this time many U.S. leaders had the idea that Canada could be annexed in the future, so it only made sense to prepare for it.