In addition to the recent letter about delayed-mail-to-the-Island-County-Clerk revelation: If your mail is not in the Post Office (in Oak Harbor) by mid-afternoon, it will not leave until early morning the next day.
All mail from Oak Harbor is transported via truck to Renton for processing, and postmarked there. The mail is then distributed and may not be delivered in the nearby region for up to two more days. Your ballots fall into this category as well. They must go through an additional step to be counted by the post office, as they are prepaid.
Weekends delay letters as well.
I suggest you take this into consideration with regard to your ballots and mail as early as possible.
The local ballot drop box at City Hall in Oak Harbor was overflowing twice when I have used that box recently, on election day. That’s not good.
Each post office in Island County is different, but similar, or worse.
The mail you put in your home delivery box with flag up, for pick-up by carrier usually does not get back to the post office by 2:30 p.m.