There is a statute in Washington (RCW 4.28.100) that allows you to serve a summons by publication in a local newspaper. You must have court approval first to do this. There are several statutory basises for this, the primary one being that the other party "being a resident of this state, has departed therefrom with intent to defraud his creditors, or to avoid the service of a summons, or keeps himself concealed therein with like intent". If your spouse is hiding out to avoid being served, you have the legal basis.
To do this, you must first file an affidavit of due diligence. This is an affidavit stating that you have done all you can to try to find the other party. You must show that you have used "due diligence". This would include things like asking family and friends, checking with employers, calling phone numbers, checking forwarding addresses, and Internet searches. Sometimes this might include hiring a private investigator to do the due diligence search.
If the court approves the process, you can then serve the other party by publishing the summons in a legal newspaper once a week for six consecutive weeks.
The Renton law firm of Mogren, Glessner & Roti, represents clients in a variety of family law cases, including divorces where we cannot locate a spouse. We have 4 attorneys for you to chose from. Please visit our web page at Washington Divorce Lawers for more information.