I would also mention that for a lot of people, the purpose in registering and/or self-identifying as a member of one party or another really has more to do with identity politics than it has with the electoral process. We here in this country like to approach politics and governance as if they were a team sport. We like to feel like we belong to a group and to compete with, demonize, and feel superior to the members of the other group(s). That's a big part of the reason we're so easy to manipulate by the fat cats.