I can't say with certainty, but WI may have the easiest absentee voting system in the country. When we are on the road as we will be next April we do the following:
1)E-mail the town clerk requesting an absentee ballot. This could also be done by snail mail.
2)Mark the ballot.
3)Sign and have the DW witness the return envelope that contains the ballot.
4)Enclose a signed copy of the email requesting the ballot.
5)Place the ballot in the envelope,seal,and drop the ballot envelope in the mail.
Walla, I have performed my civic duty.