The electrifying sounds of groovin' jump blues, Southern-fried rock 'n' roll, fervent black gospel, and the simmering sounds of the Louisiana swamp came bursting out of Nashville, Tennessee in the early 1950s courtesy of Excello Records and its sister Nashboro label. Operating out of Ernie's Record Mart ("the Record Center of the South "), Excello forged a partnership with 50,000-watt clear-channel radio station WLAC. The influential...