I am not a lawyer and this is not legal advice; question about Washington state gov-issued ID, trans-related
This gov document (about when they were adding X) seems to suggest that WA might not have a blank option: https://www.dol.wa.gov/about/docs/driver-rules/308-104-x-ces.pdf
TransEquality.org doesn't mention a blank option: https://transequality.org/documents/state/washington
I don't see anything in this WA DOL page mentioning a blank option, and the gender change request form doesn't have a box for requesting a blank: https://www.dol.wa.gov/driverslicense/genderchange.html
However, each link has contact info where you could ask about if it's a thing.
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