 The state legislature approved a provisional designation for the Lyle–Goldendale highway, Secondary State Highway 8E (SSH 8E), in 1961 that would be activated upon the completion of Primary State Highway 8 (PSH 8) between Goldendale and Plymouth.SSH 8E was formally added to the state highway system in 1965, during the planned transition to a new numbering system that would take full effect in 1970.Under the new system, SSH 8E became State Route 122 (SR 122), while PSH 8 became SR 12.