Answer: To vote in the US you must be a US citizen, and you must be 18 and you must meet your state's residency and registration requirements. No, I do not think non-citizens should be allowed to vote. The reason I think non-citizens shouldn't be allowed to vote is because they are not an inhabitant. They also aren't national of a particular country or town. Therefore, they shouldn't be a part of the voting.
Hope that helps :/