1. New England trailer trash or northern redneck. 2. Someone whose family has been in America for generations (several of which may actually reside together) but has never gotten off the ground, couch, or smack long enough to build a functional family or become a redeeming member of society.
I immediately noticed the unmistakable scent of pot after the swamp yankee drove by me in his rusty Dodge Monaco with a rotting muffler.