Phoenix Union High School District (PXU) is one of the largest and more progressive high school districts in the United States. With 23 schools, over 28,000 students, and nearly 4,000 employees, PXU covers 220-square miles of Arizona's capital city.

If the K-8 students in its 13 elementary partner school districts were included, it would be among the 25 largest unified school districts in the country, with over 110,000 students.