Blues is an original African-American musical genre that many say got its name from its connection with downhearted stories and sounds of former southern enslaved people. The main musical features of blues are call and response. Blue notes form the emotional basis of all popular music going forward into the 21st century. Led by Muddy Waters, after World War II, the blues moved north and became electrified. Today the blues are considered the purest of African-American music genres. Part of "The Genius of African-American Music" series. Please note this title contain mature themes and potentially offensive language.