Monroe Doctrine was set forth by President James Monroe in a message he delivered to the Congress of the United States on Dec. 2, 1823. It supported the independent nations of the Western Hemisphere against European interference “for the purpose of oppressing them, or controlling in any other manner their destiny.” The doctrine said also that the American continents were “henceforth not to be considered as subjects for future colonization by any European powers.” This statement meant that the United States would not allow new colonies to be created in the Americas, nor would it permit existing colonies to extend their boundaries.
Origins.
The Monroe Doctrine grew out of conditions in Europe as well as in America. The three leading absolute monarchies of Europe were Russia, Austria, and Prussia. They had pledged themselves to “put an end to the system of representative government, in whatever country it may exist in Europe.” The United States feared that these three powers (sometimes called the Holy Alliance) might also try to suppress representative government in the Americas. 
During and after the Napoleonic Wars, most of the Spanish colonies in America had taken advantage of unsettled conditions in Europe to break away from the mother country. As they won independence, these colonies formed themselves into republics with constitutions much like that of the United States. Only Brazil chose to keep its monarchy when it declared its independence from Portugal.
After Napoleon’s downfall in 1815, the monarchy was restored in Spain, and it seemed possible that the Holy Alliance might try to restore Spain’s colonies as well. The French monarchy, which had followed the policy of the Holy Alliance to the point of actually suppressing a democratic revolution in Spain, was also suspected of intending to help Spain regain its former American possessions. A rumor that France was on the point of doing so spread over Europe during 1823.
This threat disturbed not only the United States, but the United Kingdom as well. As free republics, the Spanish-American nations traded with the United Kingdom. If they became colonies again, whether of Spain or of France, their trade with the United Kingdom would certainly be cut down. The United Kingdom had steadily opposed the doctrine of the Holy Alliance and had few allies in Europe. George Canning, the British foreign minister, proposed to Richard Rush, the American minister in London, that the United Kingdom and the United States issue a joint warning against aggression by European countries in the Americas.
President Monroe was at first inclined to accept the British offer. Former Presidents Thomas Jefferson and James Madison strongly favored the idea. With the United Kingdom “on our side,” Jefferson argued, “we need not fear the whole world.” But Monroe’s secretary of state, John Quincy Adams, said that the United States should not “come in as a cock-boat in the wake of the British man-of-war.” He urged that the United States alone issue the warning. He said that the British would use their sea power to prevent European intervention in America whether they had an agreement with the United States or not. Thus the United States would have all the advantages of joint action without entering into what amounted to an alliance with the United Kingdom. Moreover, a strictly American declaration would clearly apply to the United Kingdom as well as to other European countries.
Monroe finally decided to follow Adams’s advice and proclaimed the Monroe Doctrine. He used practically the same words in the doctrine that Adams had used when he first proposed it to him.
Results.
Until the late 1800’s, Europe’s respect for the rights of the smaller American nations rested less upon the Monroe Doctrine than upon fear of the British Navy. A possible exception to this rule occurred in the 1860’s, shortly after the American Civil War, while the wartime Army and Navy of the United States were still strong. During those years, the attitude of the American government encouraged Emperor Napoleon III to give up an attempt to set up a European kingdom in Mexico. It was not until the 1880’s, when the United States began to enlarge its new Navy of modern steel ships, that the United States again had enough power to enforce the Monroe Doctrine. The United Kingdom and other countries generally ignored the doctrine until the 1890’s.
The Monroe Doctrine also served to express U.S. interest in increasing its trade with the other countries of the Western Hemisphere. However, Europe continued to get the larger share of Latin American trade, most of which went to the United Kingdom.
In some ways, the Monroe Doctrine strained relations between the United States and the Latin American countries. The nations that the doctrine supposedly protected resented the way the United States assumed superiority over them. They also feared “The Colossus of the North” more than they feared any European nation.
The Monroe Doctrine in action.
In the 1800’s, the doctrine was seldom invoked. President James Polk referred to it in 1845 during a dispute with the United Kingdom over Oregon. Secretary of State William Seward acted partly on the basis of the doctrine when he denounced French intervention in Mexico in the 1860’s. President Grover Cleveland used it when he threatened to take strong action against the United Kingdom in 1895 if the British would not arbitrate their dispute with Venezuela.
The Roosevelt Corollary.
In the early 1900’s, President Theodore Roosevelt gave new meaning to the Monroe Doctrine. He claimed that wrongdoing on the part of the smaller American nations might tempt European countries to intervene in those nations, either to collect debts or to defend the lives and property of Europeans. According to Roosevelt, the Monroe Doctrine required the United States to prevent European intervention by intervening itself. Under this “big stick” policy, the United States sent troops into the Dominican Republic in 1905, into Nicaragua in 1912, and into Haiti in 1915.
In general, President Woodrow Wilson continued Roosevelt’s policy. Wilson promised that the United States would “never again seek one additional foot of territory by conquest.” But as president, he interfered in a revolution in Mexico and tried unsuccessfully to obtain support for intervention from other Latin American countries.
The Good Neighbor Policy.
After World War I ended in 1918, the United States worked to improve relations with Latin America. Herbert Hoover made a good-will tour of South America before he became U.S. president in 1929. During his administration, he moved away from the policy of intervention in Latin America.
Hoover’s successor as president was Franklin D. Roosevelt. Roosevelt’s policy toward the Latin American countries became known as the Good Neighbor Policy. Under it, Roosevelt abandoned the practice of intervention and tried to expand trade with Latin America. He also sought Latin American cooperation in defending North and South America from countries located outside the Western Hemisphere.
During the Hoover and Roosevelt administrations, the United States gradually withdrew its forces from the smaller American countries it had occupied and gave up the special privileges it had claimed. By a series of trade agreements, it cut down high tariff barriers that had done much to keep the Americas apart. Conferences on inter-American affairs were held at Montevideo, Uruguay, in 1933; at Buenos Aires, Argentina, in 1936; at Lima, Peru, in 1938; and at Havana, Cuba, in 1940.
During World War II (1939-1945), fear of Nazi aggression brought the American republics somewhat closer. The republics met at Rio de Janeiro, Brazil, in 1942; at Mexico City, Mexico, in 1945; and at Petropolis, Brazil, near Rio de Janeiro, in 1947. They set up the Organization of American States at a meeting in Bogotá, Colombia, in 1948.
The Monroe Doctrine and isolationism.
Some people have confused the Monroe Doctrine with the policy of isolationism, or staying out of international political and economic affairs. The original statement of the Monroe Doctrine did affirm an earlier U.S. policy of isolation from Europe. That policy had been set forth by President George Washington in his Farewell Address of 1796. However, the Monroe Doctrine did not express a U.S. policy of isolation from the rest of the Western Hemisphere. On the contrary, it implied that in that hemisphere the United States would play a more active role.
