I'm assuming because this is under the history thread, it's dealing with the U.S. Senate. There are two main political parties in the U.S. which are Democratic and Republican- but there is also an Independent party, just not as big. Representatives are people who represent a certain party in, I believe, the Senate. So when it says "proportional", it's most likely referring to the fact there is an equal amount of representatives who are under the two big parties- the Democratic or Republican.
Not 100% sure and I'm sorry about that but I would say religion. I hope I helped.:)
Voter registration. To vote in Arizona, one must be a citizen of the United States and a resident of an Arizona county. A voter must be 18 years or older on or before Election Day. To be eligible to vote in an election one must register at least 29 days prior to the election.
