the term is that the belief or doctrine, held chiefly in the middle and latter part of the 19th century, that it was the destiny of the U.S. to expand its territory over the whole of North America and to extend and enhance its political, social, and economic influences. Origin of Manifest Destiny Expand.
The phrase, coined by a newspaper writer in the 1840s, implied that it was the obvious path of the United States to expand its territory as far westward as possible—the right and appropriate fate of the country.
