mail-in registration must be postmarked by October 15. The United States Election Assistance Commission maintains a list of state-by-state deadlines and a National Mail Voter Registration Form. If you are planning to vote absentee, you can find links to your state's requirements at Can I Vote?
Registration, of course, is just the beginning. Our display has materials on the Massachusetts referendum questions as well as books on some of the national issues. You can read more about issues and fact checking at CNN, NPR, or Project Vote Smart.