The West Side Union High School District was formed in July of 1912. During the district's first five years of existence, classes were held on the second floor of the new Tracy grammar school on Central Avenue. A 12-acre site for the proposed new high school building was selected during the latter part of 1912. This land cost the district $7,000 in tax funds. The new West Side High School, was started in October of 1915 and was located at 315 E. Eleventh Street in Tracy. On May 14, 2018, West Side High School was officially re-named Tracy Union High School. In 1975, the original building was declared unsafe for school purposes and was converted into an administrative complex.
- In 2006 the Tracy Community passed Bond Measure E which provided funding for the renovation and modernization of the campus. A year after buildings at Tracy High school were demolished, construction began in 2010. The new buildings included:
- A 31,000 square foot cafeteria/music building includes a 8,200 square foot cafeteria with a food court and snack stand. Seating is indoors and outside under an area protected by a permanent cover. A F.E.A.S.T. Lab (Food Education and Service Technology) kitchen and dining area will adjoin rooms for home-economics and child development classes and the Joe E. Foster Music Center will have a band room, choir room, practice rooms, music library and offices.
- A two-story 48,000 square-foot library/classroom building, with the library on the first floor and a total of 18 classrooms. Remodeling of the original Hawley-Westlake math and science building; the industrial arts and auto mechanics buildings.
The football stadium was renovated between 2011 and 2013.
In 2012 the main classroom building was named the Dr. James C. Franco Building in honor of the current superintendent for his long time dedication and service to the Tracy Unified School District. Dr. Franco was the Superintendent of Tracy Unified School District from 2002-2014. Dr. Franco came to Tracy in 1987 and was principal at Monte Vista Middle School and in 1990 became the principal of Tracy High for the next 5 years. In 1995, he was named Assistant Superintendent of Educational Services and in 2002, became the superintendent.