My most frequent rides are trails surrounding the St Louis area. I'm happy to report that I just don't see very much of such littering. When I do, I pick it up and pack it out. My theory is that trash attracts trash. Not very many people feel OK about throwing down the first wrapper but, if the area is already littered, many fewer people feel bad about adding to the mess.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.