Oregon Revised Statutes Oregon Vehicle Code § 810.220

Official traffic control devices placed or constructed by road authorities before June 27, 1975, are not required to conform to specifications and location criteria approved by the Oregon Transportation Commission. Any new or amended specifications approved by the commission under ORS 810.200 after June 27, 1975, for the placement or construction of traffic control devices do not apply to such devices in place on June 27, 1975. However within a reasonable period after June 27, 1975, traffic control devices shall be altered or relocated to comply with the manual and specifications under ORS 810.200.