PSH 5 TR became SR 706 in 1964 during the 1964 highway renumbering, in which the Washington State Department of Transportation (WSDOT) replaced the previous system of Primary and Secondary Highways with a new system called State Routes, which is still in use today.
PSH 5 TR was redesignated as SR 706 in 1964 during a highway reclassification process initiated by WSDOT, which replaced its previous system with the current State Routes designation still utilized today.