[2] Originally located in a two-story schoolhouse in 1917, the high school was given its own standalone brick structure in 1923 to accommodate a growing student body as the Portland metropolitan area and surrounding cities expanded in population; that building is used now as Cedar Ridge Middle School.

The high school continued to expand throughout the 20th century, with numerous additions and exterior buildings being added to its campus (then located at 17100 Bluff Road).

The new building, constructed on a budget of $75 million, opened in September 2012, and features various updated and new technologies absent from the previous school, including a 500-seat auditorium, outdoor learning and vocational spaces, geothermal heating, and greywater recycling.

[5] Sandy Union High School[6] was formally established in 1917,[2] with the first graduating class consisting of 12 students, all of whom were female.

[5] In 2008, voters approved a $115-million education bond for Clackamas County, $75 million of which was sequestered to use for constructing a new high school.

[4] The new school building is double the size of the previous one, with a performing arts center, 585-seat auditorium, career and technical education pod, and outdoor environmental learning area.

[21] In July 2016, Sandy High School signed an athletic sponsorship deal with the locally headquartered Nike company.