When I turned 18 in the US, they sent a postcard with return postage paid that had 2 checkboxes. First check box was that you were signing up for the draft and the 2nd was that you wished to register to vote.
Check, check, back in the mailbox. Done.
I've always just assumed this wasnt automatic so they could confirm address and that you're still alive.
Republicans continuing their quest to dilute the impact and meaning of the word treason.