We have compost programs in my area, and they usually offer free christmas tree disposal. Some programs mulch them, and I think the Parks&Rec department uses the mulch to maintain parks.

I don't really see a big downside.

I meant that lightheartedly, though I do think that doing 5+ year grows on agricultural lots for purely gimmick purposes isn't too great, at least from a resource management and ecology standpoint. I'm not here to argue against christmas trees though, I just think LePoisson's rebuttal that one instance of a thing isn't a problem because we do lots of instances of that thing is logically flawed. I'm here to argue against the bad logic, not the trees.