This distinction is predominant in states where elementary school districts and high school districts are, or were, generally separate. The Los Angeles Unified School District is a major example of a unified school district in California.

The LACHSD was catered to high school students, and was a result of annexations of high school districts in the area. On July 1, 1961, the Los Angeles City School District and the Los Angeles City High School District merged, forming the Los Angeles Unified School District.

The Long Beach Unified School District is a school district headquartered in Long Beach, California, United States. Established in 1885, Long Beach Unified School District now educates 81,000 students in 84 public schools in the cities of Long Beach, Lakewood, Signal Hill, Carson, and Avalon on Catalina Island.

Oakland Unified School District is a public education school district that operates a total of 80 elementary schools (TK–5), middle schools (6–8), and high schools (9–12).