Oregon Revised Statutes Procedure in Civil Proceedings § 14.080

(1) All other actions shall be commenced in the county in which the defendants, or one of them, reside at the commencement of the action or in the county where the cause of action arose. A party resident of more than one county shall be deemed a resident of each such county. If none of the defendants reside in this state the action may be commenced in any county.

(2) For purposes of this section, a corporation incorporated under the laws of this state, a limited partnership or a foreign corporation authorized to do business in this state shall be deemed to be a resident of any county where the corporation or limited partnership conducts regular, sustained business activity or has an office for the transaction of business or where any agent authorized to receive process resides. A foreign corporation or foreign limited partnership not authorized to transact business in this state shall be deemed not to be a resident of any county in this state.

(3) For purposes of this section, a partnership or other unincorporated association subject to being sued in its own name shall be deemed a resident of any county where any person resides upon whom summons could be served for service upon the partnership or unincorporated association.