So how do you do it? The Overseas Vote Foundation, a non-partisan org, exists purely to help overseas and military voters to ensure that their vote counts. Register to vote now!
If you're from AL, KY, OH, MN, NY, Okaloosa County Florida, or VT, you have an easier time of it than most. Check out the Overseas Vote Foundation's links to your state's super-simple opportunities to vote.
From AK, AZ, AR, CO, DE, DC, GA, IA, ME, MD, MT, NE, NV, OR, SC, SD, UT, VA, or WA? These states let you use a joint registration and absentee ballot form if you prefer to mail it in at the last minute. (But since you're a prepared traveler and reading this, you won't need to!)
We tried the registration process for New York just last week, and it seriously took us just a couple of minutes to type in our info. The system produced a super-handy, ready-to-sign PDF to mail off to our county's board of elections.
The cover letter part of the PDF they send you also includes phone numbers and email addresses so you can confirm that you're on the voter rollsso make sure you save that info and set a calendar reminder.