If you have not already registered to vote, but you are an American citizen and live in Washington state, then you still have time to register to vote!
“Online and mail registrations must be received 8 days before Election Day. Register to vote in person during business hours and any time before 8:00 PM on Election Day.“
You can register online (you’ll need a Washington State Driver License or ID) to vote in the general election.
The general election is on Tuesday, November 5th, 2019, so you should be able to register online up until October 28th, 2019.