District 13 of the Oregon State Senate comprises parts of Clackamas, Washington, and Yamhill counties centered around Sherwood, Tigard, and Wilsonville. It contains Oregon House districts 25 and 26. It is currently not represented following the death of Democrat Aaron Woods of Wilsonville on April 19, 2025.
District boundaries have changed over time. Therefore, senators before 2021 may not represent the same constituency as today. From 1993 until 2023, it covered various areas in the northern Willamette valley stretching from Hillsboro to Keizer.
The current district shrunk from its previous iterations due to population growth in Washington County, losing Keizer and all land in Marion County as well as all parts of Hillsboro.
The results are as follows: [1]
| Year | Candidate | Party | Percent | Opponent | Party | Percent |
|---|---|---|---|---|---|---|
| 1982 | Joyce Cohen | Democratic | 55.6% | Richard Smelser | Republican | 44.4% |
| 1986 | Joyce Cohen | Democratic | 53.8% | Bob Tiernan | Republican | 46.2% |
| 1990 | Joyce Cohen | Democratic | 52.0% | Bob Tiernan | Republican | 48.0% |
| 1994 | Randy Miller | Republican | 66.4% | Robert L. Lumm | Democratic | 33.6% |
| 1998 | Randy Miller | Republican | 59.3% | Ken Libbey | Democratic | 40.7% |
| 2002 | Charles Starr | Republican | 59.9% | Ken Crowley | Democratic | 40.1% |
| 2006 | Larry George | Republican | 59.0% | Rick Ross | Democratic | 40.8% |
| 2010 | Larry George | Republican | 63.2% | Timi Parker | Democratic | 36.7% |
| 2014 | Kim Thatcher | Republican | 57.7% | Ryan Howard | Democratic | 42.1% |
| 2018 | Kim Thatcher | Republican | 55.9% | Sarah Grider | Democratic | 43.9% |
| 2022 | Aaron Woods | Democratic | 58.0% | John Velez | Republican | 41.9% |