For over 100 years and spanning three centuries, the Phoenix Union High School District (PXU) has served the city's educational needs. Beginning in 1895 with four classrooms and 90 students, the District has mirrored the mercurial growth of Phoenix.

Today, over 28,000 students attend 11 comprehensive high schools, six small specialty schools, three alternative schools, three micro schools, and the Phoenix Digital Academy. The District covers a 220-square-mile area fed by 13 elementary districts, making it one of the largest secondary school districts in the nation.

The District’s namesake, Phoenix Union High School, was the only school for several years, located downtown at 7th Street and Van Buren. It was the largest high school west of the Mississippi at the height of its enrollment. 

In 1926, Carver High School opened to accommodate the growing number of African American students. It closed in 1954 with the integration of schools. 

Phoenix Union’s Board of Education established Phoenix College in 1920 as a junior college. It operated until the state legislature passed an act creating and maintaining junior colleges in Arizona. 

In 1938, with Phoenix Union’s enrollment of over 5,000 students, a new high school was built. North Phoenix High School opened its doors to 1,517 students in 1939. The name was changed to North High School in 1959. 

Between 1949 and 1957, the district built an additional five schools—West, Camelback, South Mountain, Central, and Carl Hayden. Continued growth led to the construction of Alhambra, East, and Maryvale in the 1960s, and Trevor G. Browne in 1972. 

Declining enrollment during the 1980s forced the closure of four schools. North High closed in 1981, only to reopen in 1983. Phoenix Union ended its reign after 87 years in 1982, closing along with East and West high schools. West reopened in 1985 as Metro Tech Vocational Institute of Phoenix and eventually became the magnet high school Metro Tech in 1999, home to career/technical programs for grades 9-12. 

Two alternative schools opened in the 1970s—Bostrom Alternative Center and Desiderata. 

Cesar Chavez was the first new Phoenix Union high school built in 27 years, and the first in the town of Laveen, opening in 1999. 

A unique partnership between businesses and the district created the Suns-Diamondbacks Academy, now Linda Abril Educational Academy, an alternative school for at-risk youth, which moved into its new building in January 2002. 

In 2007, Betty H. Fairfax High School became the district's 11th comprehensive high school, opening its doors to students in Laveen.

A small school initiative ushered in two new specialty schools in 2006—Bioscience High School, featuring a rigorous science- and math-focused curriculum, and Cyber High School, a computer-based school. Bioscience moved into its downtown campus in the heart of the biotech community in 2007. Cyber closed in 2010. 

Franklin Police and Fire High School, a small school featuring public safety career classes in areas like law enforcement and firefighting, opened the same year at the historically restored Franklin Elementary School. 

A 2011 construction bond built two more campuses, opening in 2016. In 2012, PXU opened Camelback Montessori, the first high school of its kind in Arizona.  Sixteen years after Suns-Diamondbacks Education Academy began, it moved to its first permanent home under a new name, Linda Abril Educational Academy. Another small specialty school, Phoenix Coding Academy, opened its first class for the 2016-17 school year. 

Wilson College Prep became the next school to open in 2017. In 2020, the PXU Digital Academy (now Phoenix Digital Academy) found a permanent home, and the Maryvale Gifted and Talented Academy space was renovated to provide more opportunities for students. In early 2021, Phoenix Union launched its first micro school in South Phoenix with the approval of Advanced Readiness at Chavez High (ARCH) located at Cesar Chavez High School in Laveen.

In the fall of 2022, the District added PXU City to its portfolio. PXU City, where the entire city of Phoenix is the classroom, will provide students with the opportunity to take courses at multiple campuses while participating in clubs, sports, and the arts at any school in the PXU portfolio. 

In 2023, Phoenix Educator Prepatory opened its doors to the community and serves as a hub for students wanting to enter the education profession. Students can take internships and earn an associates degree while in high school. The mission of Educator Prep is to prepare the next generation of educators, counselors, social workers, and psychologists to create a self-sustaining employment model for the District to combat state-wide staffing shortages. All initial costs associated with this school will be funded by a generous grant from the Pharos Foundation.

• Phoenix Union High School, 1895 (closed 1982)

• Carver High School, 1919 (closed 1954)

• Phoenix Technical School, 1935 (closed 1955)

• Phoenix Flying School, 1947 (closed 1960)

• North High School, 1939

• West High School, 1949 (closed 1983)

• Camelback High School, 1953

• South Mountain High School, 1954

• Carl Hayden Community High School, 1957

• Central High School, 1957

• Alhambra High School, 1962

• Maryvale High School, 1963

• East High School, 1964 (closed 1982)

• Cyesis Center, 1964

• Trevor G. Browne High School, 1972

• Area Vocational Center, 1975 (closed 1985)

• Bostrom Alternative Center for Education, 1976

• Desert Valley High School, 1977 (closed 1991)

• Desiderata, 1977

• Phoenix Vocational Academic Center, 1980 (closed 1985)

• Metro Tech Vocational Institute of Phoenix, 1985

• Cesar Chavez High School, 1999

• Cyber High School,  2006 (closed 2010)

• Betty Fairfax High School, 2007

• Suns-Diamondbacks Educational Academy, 2001 (name changed 2016)    

• Bioscience High School, 2006

• Franklin Police and Fire High School, 2007

• Camelback Montessori, 2012 

• Linda Abril Educational Academy, 2016 (formerly Suns-Diamondbacks Educational Academy)

• Phoenix Coding Academy, 2016

• Phoenix Union Wilson College Prep, 2017

• Gifted and Talented Academy, 2017 

• Phoenix Digital Academy, 2020

• Advanced Readiness at Chavez High (ARCH), 2021

• PXU City, 2022

• Educator Preparatory, 2023