How and When Do I Return My Ballot?   Ballots May be Mailed: Ballots must be postmarked on or before election day to be valid. Do NOT assume that your ballot will be postmarked on the same day you drop it off at the post office or in a US mailbox.    Ballots May be Deposited in a Ballot Drop Box: If you return your ballot on election day, you are advised to take it to a permanent ballot drop box prior to 8:00 p.m. Click here for Ballot Drop Box Locations   Ballots May be Delivered in person to the Thurston County Auditor's Office: Address: 2000 Lakeridge Dr. SW, Olympia Click here for Driving Directions and Map