JAMES Monroe, the fifth president of the United States, enunciated the Monroe Doctrine in 1823, which proclaimed that the Western Hemisphere (basically North and South America) would be off-limits to further colonisation by European countries, whilst respecting the existing European colonies in the Americas.
Since 1823, the American push westward, the gradual acquisition of former Spanish empire territories (Texas, California, Puerto Rico, Hawaii, Guam and the Philippines), and the purchase of Alaska from Russia in 1867, all contributed to the extension of Pax Americana.
