IV.

Further Development in the 19th Century

As far as the United States was concerned, the Monroe Doctrine meant little until the 1840s, when presidents John Tyler and then James Polk used it to justify U.S. expansion. In 1845 Polk invoked the doctrine against British threats in California and Oregon, as Tyler had done in 1842 against French and British efforts to prevent the U.S. annexation of Texas. In 1848 Polk warned that European involvement in the Yucatán could cause the United States to take control of the region. Despite Polk's use of the doctrine and its increasing popularity in the 1850s, the American Civil War greatly reduced its effectiveness during the 1860s; hence, Spain's reacquisition of the Dominican Republic (1861) and France's intervention in Mexico (1862-1867) went largely unopposed.

During the 1870s and 1880s the Monroe Doctrine took on new meaning. The United States began to interpret it both as prohibiting the transfer of American territory from one European power to another, and as granting the United States exclusive control over any canal connecting the Atlantic and Pacific oceans through Central America. The latter claim was recognized by Britain in the Hay-Pauncefote Treaty in 1901. The United States continued to expand the meaning of the doctrine when President Grover Cleveland successfully pressured Britain in 1895 to submit its boundary dispute with Venezuela to arbitration.