I doubt that there is an aluminum can lying in a ditch anywhere in North Carolina right now. The can collectors have gotten more numerous in hard times, and the warmer weather is drawing them out in droves.
Your observation of the established v. influx residents may be spot-on. Most littering follows a pattern, and I think sometimes, a trashy stretch just invites more. We have probably close to a couple miles of roadfront on this farm and the kids' adjoining land, very little comparatively on two others, and virtually none on a fourth. I see the whole gamut of this behavior.
Hardly anything ends up on the highway frontage, since people are traveling at higher speeds and there's a bad-enough curve that would discourage anyone from taking hands off the wheel to drop a window to toss trash. The county road that tees with that highway gets lots of soft drink containers and chip bags, almost all off them leading up to the stop sign at the intersection.
This route is a favorite commute for the prison staff, that facility being out a few miles past us on the Roanoke River. I suspect that this is far enough for someone getting off work to have stoked up with a snack and soft drink on the way home, and that as they slow for the stop, they lower a window and toss the paper and can or bottle along here.
I pick up trash when I see it. I try to at least get it before the state mows the shoulders, since one piece gets to be an aggravating set of shreds if I don't. Also, as I said above, if there is already trash along a stretch, it seems to breed more.
Keep some trash bags or a bucket in yoru truck, and try to police it as much as you can. I have seen that soem ploaces that have "adopt-a-highway" signs do not beem to invite as much trash as they once did...so maybe the signs make people feel guilty enogh to hold onto it for a mile or so longer.
