"The word redneck was first cited in Scotland. In Scotland, the National Covenant and The Solemn League and Covenant (a.k.a. Covenanters) signed documents stating that Scotland desired a Presbyterian Church Government, and rejected the Church of England as their official church (the Church of England was never the 'official' church in Scotland, which was, of course, the Church of Scotland. What the Covenanters rejected was episcopacy--rule by bishops--the preferred form of church government in England.) Many of the Covenanters signed these documents using their own blood, and many in the movement began wearing red pieces of cloth around their neck to signify their position to the public. They were referred to as Rednecks. "
Usage of the term "Redneck" generally differs from Hick and Hillbilly, because Rednecks reject or resist assimilation into the dominant culture, while Hicks and Hillbillies theoretically are isolated from the dominant culture. In this way, the Redneck is similar to the word Cracker.
http://en.wikipedia.org/wiki/Redneck