District boundaries have changed over time. Therefore, senators before 2021 may not represent the same constituency as today. From 1993 until 2003, the district covered parts of the northern Willamette Valley; from 2003 until 2013, it stretched from Rockcreek west to Forest Grove; and from 2013 until 2023, it stretched slightly north to cover Helvetia.
The current district is very similar to its previous iterations, changing only by losing North Plains and parts of south Hillsboro and adding rural land south of Cornelius and Forest Grove.