I completely agree with your thought that U.S. expansion was motivated by military, diplomatic, and economic aspirations, all which were legitimized by Manifest Destiny. Minor Keith's moves in Central America was a replica of U.S. imperialism substituting the use of economic might instead of gunpowder to assert control over the economies of other nations. His tireless pushing regardless of exploiting workers best captures the exploitative nature of American colonialism. While he assisted Costa Rica in the development of its infrastructure, it was more so for the sake of U.S. business than anything else, as a best example of government actions in the Pacific.