From Multnomah County Elections:
It is Too Late to Mail! Return Your Ballot to an Official Ballot Drop Site.
Return your voted ballot to an Official Ballot Drop Site. It is too late to return your ballot by mail. Postmarks do not count in Oregon. In order to ensure your ballot is received by the county elections office before 8:00 PM on Election Night, November 3 you must return it to any Official Ballot Drop Site in Oregon. In Multnomah County, you can return your ballot to any 24-hour Official Ballot Drop Site or to any 24-hour Multnomah County Library Drop Site. Please return your voted ballot to the Official Ballot Drop Site closest to you (Google Map) to reduce congestion at other locations. Ballots are picked up from library locations and Official Ballot Drop Boxes by teams of sworn election officials on a daily schedule. All 30 of Multnomah County Official Ballot Drop Sites, including library locations, are safe and secure. All Official Ballot Drop Sites are listed at multco.us/dropsites.