District 20 of the Oregon State Senate comprises northern Clackamas County and encompasses the communities between Oregon City and Happy Valley. It is composed of Oregon House districts 39 and 40. The district is currently represented by Democrat Mark Meek of Gladstone.
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 Eugene metropolitan area; from 2003 until 2013, it stretched from Clackamas to Canby while not extending as far east as Happy Valley; and from 2013 to 2023, it did not extend as far north, with only part of Clackamas and none of Happy Valley included, while stretching farther east to reach Estacada.
The results are as follows:[1]
| Year | Candidate | Party | Percent | Opponent | Party | Percent | Opponent | Party | Percent | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1982 | Margie Hendriksen | Democratic | 52.2% | George F. Wingard | Republican | 47.8% | No third candidate | |||||||||||
| 1986 | Grattan Kerans | Democratic | 64.2% | Scott Carpenter | Republican | 31.2% | Bob Fauvre | Libertarian | 4.6% | |||||||||
| 1990 | Grattan Kerans | Democratic | 63.2% | Peter Swan | Republican | 36.8% | No third candidate | |||||||||||
| 1994 | Pete Sorenson | Democratic | 64.5% | Jimi Mathers | Republican | 28.0% | Jeanne Dellinger | Nonpartisan | 7.5% | |||||||||
| 1998 | Susan Castillo | Democratic | 79.4% | Scott Austin | Republican | 20.6% | No third candidate | |||||||||||
| 2002 | Kurt Schrader | Democratic | 55.6% | Jesse Lott | Republican | 44.4% | ||||||||||||
| 2006 | Kurt Schrader | Democratic | 96.1% | Unopposed | ||||||||||||||
| 2010 | Alan Olsen | Republican | 50.2% | Martha Schrader | Democratic | 49.8% | No third candidate | |||||||||||
| 2014 | Alan Olsen | Republican | 52.5% | Jamie Damon | Democratic | 47.1% | ||||||||||||
| 2018 | Alan Olsen | Republican | 51.9% | Charles Gallia | Democratic | 46.1% | Kenny Sernach | Libertarian | 1.9% | |||||||||
| Mark Meek | Democratic | 50.3% | Bill Kennemer | Republican | 49.5% | No third candidate | ||||||||||||