Oregon Revised Statutes Highways, Roads, Bridges and Ferries § 366.220

(1) The Oregon Transportation Commission may select, establish, designate, construct, maintain, operate and improve or cause to be constructed, maintained, operated and improved a system of state highways within the state, which highways shall be designated by name and by the point of beginning and terminus thereof. The system of state highways shall include such other highways as may from time to time be selected and adopted by the commission pursuant to law and all highways adopted and classified as secondary state highways which are subject to and qualified for construction, improvement, betterment and maintenance as are other state highways.

(2) The commission may classify and reclassify the highways comprising the state highway system as primary and secondary highways. Secondary highways may consist of newly established highways, reclassified primary highways and county roads selected pursuant to ORS 366.290.