Which of these capital cities was also once the capital of the U.S.? Correct
Among the capital cities listed, Annapolis, Maryland, is the only city that was once the capital of the United States. Annapolis briefly served as the capital of the United States from 1783 to 1784, before the federal government moved to its more permanent location in Philadelphia. Richmond, Virginia, is historically significant as the capital of the Confederacy during the Civil War but was never the capital of the United States. Harrisburg, Pennsylvania, and Boston, Massachusetts, have not served as the national capital. Therefore, among the options provided, Annapolis, Maryland, stands out as the correct city that was once the capital of the United States.