West's Revised Code of Washington Annotated: Currently updated edition held by Geo. Wash. U. Law Library. Accessible to Georgetown Law students under reciprocal state statutes collection program or via Interlibrary Loan.
In Westlaw, see also state legislative history, statutes annotated - historical, bill tracking, bill tracking historical, and proposed & enacted legislation.
In Lexis, full-text bills, advance legislative service, and legislative bill history may be in Statutes and Legislation.
In Bloomberg Law, text of enacted legislation may be found through State Laws & Regulations > Legislative > Session Laws or Acts.
LLMC Digital may contain digitized historical senate and house journals as well as historical state statutes and/or session laws (Online Services > Browse Collections > U.S. States and Territories > State Name > Legislative).