Why do you think that the thirteen colonies were limited to thirteen

To keep Republican and Democratic states relatively even. (Don't quote me on this, I suck at history but at least it's an answer. It's useless anyway, we're learning about dead people.)

what the first or next guy says

an interest group is an organization whose members share common concerns, and try to influence government policies that impact those concerns. elected officials frequently complain about the influence of "special interests" on american politics.