Around the close of the nineteenth century and the beginning of the twentieth, the United States was very much an imperialist country. While the imperialism of the 1900s may have departed from past actions in terms of size and ambition, but the fundamental reasons and drive for expansion remained the same throughout much of America's history. Past expansion of the US includes the Manifest Destiny-driven push to the West coast, the annexation of Texas, and the purchase of Alaska.
Manifest Destiny, which was one of the essential reasons for US expansion from coast to coast, was largely motivated by American nationalism. Nationalism was also a major factor in motivating many of the expansionist actions of the US around the 1900s. The Spanish-American war was fought as a direct result of a nationalistic, jingoistic furor whipped up by yellow journalists in the United States. Manifest Destiny was a feeling that we, as a nation, had a right and duty to expand for our best interests. If anyone were to stand in our way, so be it. This feeling still existed around the time of the Spanish-American war, and also was a basis for our expansion into Cuba and the Philippines. Theodore Roosevelt personifies this feeling in Document F, "If a nation shows that it knows how to act with reasonable efficiency and decency in social and political matters, if it keeps order and pays its obligations, it need fear no interference from the United States.".
The separation and annexation of Texas from Mexico in the 1840s still shared much of the same impetus to expand as expansion in the 1900s, with nationalism again playing a major role. Settlers colonizing Texas felt strong nationalistic ties to the United States after their host, Mexico, tried to impose their laws on them. This, which led to the Mexican-American war and annexation of Texas, is a blatant example of imperialism like that which took place in the 1900s, even if it wasn't state-sponsored originally.
