Oregon Revised Statutes Counties and County Officers § 201.040

(1) Beginning at a point where the northern boundary of the state is intersected by the projection north of the range line between ranges 5 and 6 west of the Willamette Meridian; thence south along such projection and range line to the southeast corner of township 4 north, range 6 west; thence westerly along the township line between townships 3 and 4 north of the Willamette Base Line and along the projection westerly of such line to the western boundary of the state; thence north along such western boundary to the northwest corner of the state; thence easterly along the northern boundary of the state to the point of beginning.

(2) The line of boundary between Tillamook and Clatsop Counties is the south boundary line of Clatsop County, as described in subsection (1) of this section.