While purchasing territory from another country would be an unusual move for a modern U.S. president, much of America’s states and territories today came through purchase or expansion.

A strong majority of Americans, 66%, are opposed to U.S. territorial expansion accomplished “by invading other countries and territories,” according to a recent poll from More in Common.

In the 19th century, the phrase was used to invoke the divine justification for the United States to expand its territory westward all the way to the Pacific -- in bloody campaigns that saw the ...