Blown out holiday lights often get tossed in the garbage only to sit in a landfill forever. The following locations will take holiday light strings for recycling:
The United Group in Snohomish have said they will take holiday lights, when contacted with this question. Their materials accepted list does not include holiday lights, so it may be best to contact them to make sure.
McLendon Hardware stores recycle holiday lights, but only during holiday the season. The closest location to Snohomish County is in Woodinville.
You can replace your old holiday lights with LED lights through this mail-in program at HolidayLEDS.