Its called howdying. You howdy everyone you see, no matter what.
I've noticed in Fayetteville and Bentonville (home of Walmart), where there are a lot of new comers to the Ozark Mountains, they have a peculiar way to howdy people. These folks stick their arm out the window of their car and raise their middle finger; somehow it doesn't seem as friendly as the old fashioned wave.
Everybody drives down the middle of the dirt roads; why do these folks get so uptight when you drive that way on the pavement?