Pax Americana (Latin for "American Peace") is a term applied to the historical concept of relative peace in the Western Hemisphere and later the Western world resulting from the preponderance of power enjoyed by the United States starting around the start of the 20th century. Although the term finds its primary utility in the later half of the 20th century, it has been used in various places and eras, such as the post-Civil War era in North America and globally during the time between the World Wars.
Pax Americana is primarily used in its modern connotations to refer to the peace established after the end of World War II in 1945. In this modern sense, it has come to indicate the military and economic position of the United States in relation to other nations. The term derives from and is inspired by the Pax Romana of the Roman Empire, the Pax Britannica of the British Empire and the Pax Mongolica of the Mongol Empire.