The Monroe Doctrine was a foreign policy statement, not an official law passed by Congress or a treaty ratified as binding law.
Based on US 5th President James Monroe, the Monroe Doctrine was a 19th‑century U.S. foreign policy statement declaring that the Western Hemisphere was closed to new European colonization. This meant any acquisition of land by Europeans, prior to December 2, 1823 would dismissed, cut and consider any revisited European interference in the Americas, a hostile act against the United States. But online within the Doctrine line.
In America, President Monroe would pledged that the United States would stay out of European wars and not disturb existing European colonies in the Americas. Until the Great War (WW 1 and 2) challenged those boundaries.
Too Big for El Britches
Between 1823 and 1904, the United States mostly used the Monroe Doctrine as a defensive political warning to Europe while gradually expanding its own power across North America and into the Caribbean, without yet claiming the full “police power” over Latin America that came with the Roosevelt Corollary in 1904.
There was limited naval capabilities to truly enforce any growth prevention in area, with the US ironically still needing the British naval power and parallel British interests to help deter other European recolonization in Latin America.
In 1904, Theodore Roosevelt added the “Roosevelt Corollary,” asserting that the United States could intervene in Latin American nations to stabilize them and prevent European involvement, especially over debts.
As a result, U.S. forces intervened in countries such as Santo Domingo (Dominican Republic), Nicaragua, and Haiti, actions many Latin Americans viewed as imperialistic.
Calling Cobbs On Land
The Doctrine did not create specific taxes, tariffs, or fees; instead, it shaped the environment in which U.S. trade and investment expanded.
By discouraging new European colonies in the Americas, the Doctrine helped keep Latin American markets more open to U.S. and British trade over the 19th century, indirectly supporting U.S. commercial growth.
Later reinterpretations (like the Roosevelt Corollary and early 20th‑century interventions) were often used to protect U.S. investments, debt collections, and resource interests in the Caribbean and Central America, but again those gains are embedded in overall trade and investment figures, not broken out as “Monroe Doctrine income.”