Oregon Revised Statutes Counties and County Officers § 202.020

Whenever it is desired to form a new county out of one or more then existing counties or to change the boundaries of then existing counties, a petition praying for the formation of such new counties or for the change of the boundaries of then existing counties, describing the territory proposed to be incorporated in the new county or changed from one county to another, together with the name of the proposed new county, if for that purpose, or the name of the then existing county to be eliminated, if any county would be eliminated by the change of boundaries as proposed, signed by a majority of the electors registered in the territory to be embraced in the new county or registered in the territory to be embraced in the change of county boundaries, shall be presented to the county court of each county to be affected by the proposed formation of a new county. Where any existing county would be eliminated by such change of county boundaries the petition shall be signed by not less than 40 percent of the electors of the county to be eliminated.