ORS § 201.290
The boundary of Tillamook County is as follows: Beginning at the southwest corner of township 4 north, range 5 west, Willamette Meridian; thence five miles south; thence six miles west; thence two miles south; thence one mile east; thence one mile south; thence one mile east; thence one mile south; thence one mile east; thence one mile south; thence two miles east; thence one mile south; thence two miles east; thence one mile south; thence two miles east; thence one mile south; thence one mile west; thence one mile south; thence two miles west; thence two miles south; thence two miles west; thence one mile south; thence one mile west; thence one mile south; thence one mile west; thence two miles south; thence one mile west; thence three miles south; thence one mile west; thence one mile south; thence one mile east to the northwest corner of section 5, township 2 south, range 6 west, Willamette Meridian; thence south 15 miles to the northwest corner of section 20, township 4 south, range 6 west; thence west 16 miles to the center of township 4 south, range 9 west; thence south to the northwest corner of the southwest quarter of the southwest quarter of section 3, township 6 south, range 9 west; thence east to the northwest corner of Polk County; thence south to the northeast corner of Lincoln County; thence west along the northern boundary of Lincoln County to the western boundary of the state; thence north along such western boundary to the south boundary line of Clatsop County; thence east along the south boundary line of Clatsop County to the point of beginning.
ORS 201.290