Look here for info:
http://www.dol.wa.gov/driverslicense/moving.htmlHow to get a Washington State driver license
If you have a valid out-of-state driver license
* Visit a driver licensing office.
* Bring with you:
o Proof of identification, including your out-of-state license.
o Cash or check to pay the $45 fee for your first Washington driver license ($20 for your application and $25 for your license).
o Your social security number, which is mandatory to help enforce child support laws. Your social security number will be verified but does not appear on your license.
* Complete a driver license application, which includes:
o Address.
o Physical and mental fitness statement.
o Previous driver licenses information (if any).
o Suspensions, revocations, or cancellations of prior driver licenses.
* Take a vision test and demonstration of color recognition.
* After completing the steps above, written and drive testing is waived unless there is a medical/physical condition which indicates that testing is required.
* You must turn in your out-of-state license to the Department of Licensing so it can be invalidated.
If you still have a valid license it should be a fairly simple process, WA only mentions OUT-OF-STATE which Canada is of course out of state.