The "New World" ballad tradition, consisting of ballads written in North America, was as influential as the Old World tradition to the development of Appalachian music. New World ballads were typically written to reflect news events of the day, and were often published as broadsides. New World ballads popular among Appalachian musicians included "Omie Wise", "Wreck of the Old 97", "Man of Constant Sorrow," and "John Hardy". Later, coal mining and its associated labor issues led to the development of protest songs, such as "Which Side Are You On?" and "Coal Creek March".