“The earliest printed uses of the word red-neck in a coal-mining context date from the 1912-1913 Paint and Cabin Creeks strike in southern West Virginia and from the 1913-1914 Trinidad District strike in southern Colorado. It is not known where the term originated. It originated as a negative epithet. Apparently, coal operators, company guards, non-union miners, and strikebreakers were among the first to use the term "redneck" in a labor context when they derided union miners with the slur. According to industrial folklorist George Korson, non-union miners derisively called strikers "rednecks" in the Appalachian coalfields. The best explanation of redneck to mean "union man" is that the word refers to the red handkerchiefs that striking union coal miners in both southern West Virginia and southern Colorado often wore around their necks or arms as a part of their informal uniform.”
—Patrick Huber, “Red Necks and Red Bandanas: Appalachian Coal Miners and the Coloring of Union Identity, 1912-1936,” Western Folklore, Winter 2006.