Oregon constitution
Article XVIII: schedule
Section 11

Until otherwise provided by law, the judicial districts of the State, shall be constituted as follows: The counties of Jackson, Josephine, and Douglas, shall constitute the first district. The counties of Umpqua, Coos, Curry, Lane, and Benton, shall constitute the second district.–The counties of Linn, Marion, Polk, Yamhill and Washington, shall constitute the third district.–The counties of Clackamas, Multnomah, Wasco, Columbia, Clatsop, and Tillamook, shall constitute the fourth district–and the County of Tillamook shall be attached to the county of Clatsop for judicial purposes.