The mindset that came to be identified with Manifest Destiny made a huge impact upon the ways of the United States of the mid-1800's, although the beginnings of the attitude were present long before then.
The philosophy of Manifest Destiny suggested that the United States was destined by God to spread its supremely desirable form of government and approach to society to the rest of the world. By increasing the American influence in foreign countries, the United States was bringing blessings to those countries that would not have been otherwise achieved.
God has predestinated, mankind expects, great things from our race... The rest of the nations must soon be in our rear. We are the pioneers of the world;...national selfishness is unbounded philanthropy; for we can not do a good to America but we give alms to the world.
Manifest Destiny was a consideration as the United States added territory through negotiations with Mexico, England, and Russia. After the conclusion of the 1898 Spanish-American War, the United States influence spread to a world-wide involvement, which many justified on the basis of Manifest Destiny.
Manifest Destiny had a very profound impact on U.S. foreign policy both in terms of the westward expansion towards the Pacific and in terms of relationships with other countries. The United States, of course, was initially comprised of the original 13 colonies-turned-states. Its relentless expansion, most prominently with the Louisiana Purchase, the earliest manifestation of American expansionism, meant that the newly-established nation would inevitably run up against the interests of additional colonial powers, especially the British and Spanish, as well as against Mexico. The westward movement of American settlers, supported through the growing military capabilities of the U.S. Army, entailed a continuous series of confrontations with Native tribes, for whom these European interlopers constituted a foreign invasion in and of itself. The most significant direct confrontations, in addition to the genocidal practices involving the Native populations, involved Mexico and Great Britian, the former to the southwest, the latter to the north. The Mexicans would eventually be forced to cede tremendous territories to the Americans, including the temporarily independent and sovereign Republic of Texas, and the British would take measures to ensure that U.S. expansionism was curtailed at the Canadian frontiers.
Overseas, Manifest Destiny was viewed as a symbol of growing U.S. might and influence. The European character of most of the settlers staking claims across the North American continent meant an intense interest in these developments in European capitals. The growth of the U.S. Navy would facilitate the expansion of trans-Atlantic and trans-Pacific trade, as commercial shipments were less likely to be upset by foreign naval patrols. Manifest Destiny represented the growth of a new global power, although that global influence would not be felt until the global conflagrations that would sweep Europe during the 20th Century.
Manifest Destiny had an impact on our foreign policy. The United States had been gradually spreading its control over the land from the Atlantic Ocean to the Pacific Ocean. Many people believed it was our duty to do this. Others felt it was destined by G-d for us to spread our way of life across the land. Others felt our way of life was superior, and, therefore, we should spread it. Once we reached the Pacific Ocean, in what is now the mainland United States, people began to take the concept of Manifest Destiny to a new level.
The United States was looking to become a world power by 1900. People began to say it was our duty to spread our superior way of life across the world. We could help other “less fortunate” people by sharing our way of life and showing them how to govern themselves. Thus, we jumped on the opportunity to go to war with Spain when we received reports that the Spanish were mistreating the Cubans. When a United States warship exploded in Havana Harbor, we went to war with Spain. As a result of this war, we got control of colonies in the Pacific Ocean and the Caribbean Sea. We were now an imperial power and could spread our way of life to other places.
We continued to spread our way of life by getting involved in Latin America. We helped Panama become a country when it revolted against Colombia. We wanted to build a canal in the region, and Colombia refused to agree to a deal with us. We intervened in the Dominican Republic and Nicaragua to help maintain stability in the region. These actions allowed us to spread our influence beyond our borders, pushing the ideas of Manifest Destiny onto an international level.