Oregon's 18th Senate district

District 18 of the Oregon State Senate comprises parts of central Washington County centered around Aloha and encompassing parts of Beaverton and Hillsboro. It is composed of Oregon House districts 35 and 36. It is currently represented by Democrat Wlnsvey Campos of Aloha.

Election results
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 western Willamette Valley; from 2003 until 2013, it covered Tigard and parts of southwest and downtown Portland; and from 2013 until 2023, it only shifted slightly, covering more of downtown Portland as well as the city of Durham and a small chunk of Clackamas County. The results are as follows: