America's rise to world power was brought about by both internal and external forces. Traditionally, from the time of the Monroe Doctrine, the United States had pursued a more or less isolationist course with repect to the European world. But the industrial revolution, which generated enormous changes in transportation and communication, put Americans in much closer touch with the rest of the world, whether they wished it or no. Expanding production created a desire for foreign markets and sources of raw matrerials. At the same time, the age of neo-colonialism generated competition among the great powers for furhter expansion in to less-developed parts of the world, And Americans were reluctant not to join in, even though traditional American policy had eschewed such behavior.