Updating my advice given timing: —If you already have a mail ballot, you can put it in a drop box. —If you must mail it, & are in a state with a grace period (=rule is postmark by Election Day), you should go to counter & watch them postmark. —If your state has no grace period... it is late.
*so important*: if you’re voting by mail, assume the USPS will delay because it’s its policy. You can: —put it in drop box —go to counter to watch them postmark in front of you —if you’re dropping it in a mailbox, do it VERY EARLY.