A senatorial district, when more than one county shall constitute the same, shall be composed of contiguous counties, and no county shall be divided in creating such senatorial districts. Senatorial or representative districts comprising not more than one county may be divided into subdistricts from time to time by law. Subdistricts shall be composed of contiguous territory within the district; and the ratios to population of senators or representatives, as the case may be, elected from the subdistricts, shall be substantially equal within the district.
Structure Oregon constitution