District boundaries have changed over time. Therefore, senators before 2013 may not represent the same constituency as today. From 1993 until 2003, the district covered parts of Southern Oregon; from 2003 until 2013, it shifted to cover all of Hood River County and eastern portions of Clackamas and Multnomah counties, including a panhandle in Clackamas; and from 2013 until 2023, it shifted east, losing most of southeastern Clackamas County and its previous panhandle but gaining a panhandle covering Happy Valley and outer southeast Portland surrounding Powell Butte.
The current district is similar to its previous iterations. The district no longer includes any part of Portland, Clackamas, or Happy Valley and uses the Clackamas River as its northern boundary in Clackamas County. It has added the communities of Beavercreek, Canby, and Estacada in Clackamas County and Chenoweth, Mosier, and The Dalles in Wasco County.