The Department of Transportation may enter into cooperative agreements with the federal government and with any county or city for the location, adoption, construction and maintenance of a throughway either within or without the corporate limits of any city, with respect to highways under the exclusive jurisdiction of the department, roads under the jurisdiction of the county court or board of county commissioners and streets under the exclusive jurisdiction of cities, and may, in such agreements, agree upon the allocation of costs of the project, the manner and method of maintenance and all other relevant matters.
Oregon Legal Code