Icontemporary times, popular music embraces the songs of minstrel and vaudeville shows, dance music, ballads, musical comedy, music hall and all other kinds of music that you might expect to hear people whistling or humming in the street. Patriotic popular songs have seen many countries through depression, wars, and much of the economic, political, and social change of the past hundred years. But for the most part, popular music in the 20th century originated in the U.S., and has been...