I actually just attended a webinar on the laws of promotions this week and the host defined an illegal lottery as prize + chance + consideration. The consideration is that they have to buy the track from you to participate. Chance is the voting. And the prize is obvious. In my non-lawyer opinion, it sounds like you may be in a legal grey area when it comes to your setup and may want to remove either the chance or consideration aspect, which would make it a “sweepstakes” or “competition” and thus legal. Then, as long as you have thorough promotion rules posted alongside the promotion, you should be covered.