As BMatthews points out, the lift distribution always goes to zero at the wing tips. Suppose you had a rectangular planform wing that had constant chord and wing section, and no twist (the simplest wing you could build). If you were to look at the lift distribution, the center sections would "generate" more lift than the outboard sections. Suppose you were to cut the tips off of the wing so that the span was reduced by half. The lift at the new wing tips would now be zero. I think this is interesting because it is easy to look at a plot of a lift distribution and see that the center sections carry more lift. However, without the outboard sections there, the inboard sections wouldn't generate nearly as much lift. So I would make the argument that, although the outboard sections "carry" less lift, their presence is responsible for some of the lift carried by the center sections. Lift and drag can be slippery topics to get your brain around...