The rampant occupation of the American West was encouraged by an ideology existing in the United States at the time and by the conditions offered by the American government. During the 19th century, an ideology known as Manifest Destiny was formulated, which claimed that the United States was predestined (chosen) by God to form a great nation. This “divine vocation” was used as a pretext to justify the violence against indigenous people, for example.
The incentive of the American government came with the Homestead Act, or the Settlement Act, enacted in 1862. This law, instituted during the Abraham Lincoln government, offered lots of land in the west at a very low price for interested Americans and demanded in exchange that the land sold was inhabited and cultivated for a minimum period of five years. Thus, farmers sought new land to cultivate and new markets to dominate, and miners sought opportunities for wealth and prosperity at new points of exploitation.
The House Committee on Un-American Activities (HUAC) was an investigating committee which investigated what it considered un-American propaganda. Specifically commmunist influence inside and outside the US government after the WWII.
Answer: there were two immediate ones: America's support the ongoing struggle by Cubans and Filipinos against Spanish rule, and the mysterious explosion of the battleship U.S.S. Maine in Havana Harbor.
