In or about 1888, it is my understanding that the Glendale and Pasadena school districts agreed upon a boundary line between their respective districts. The line they established is the one that is currently the boundary line between the Glendale and La Cañada Flintridge school districts.
Then, in 1976, the two unincorporated areas of La Cañada and Flintridge elected to incorporate. The architects of the new city chose to establish the western boundary of the city at Pickens Canyon, rather than making it contiguous with the boundary of the La Cañada school district. Thus, a large area of the new city was designedly not included within the LCUSD.
This is the historical accident that caused a portion of western La Cañada Flintridge to be within the Glendale Unified School District. At the time, the Glendale schools were among the highest performing in California and were well known for their excellence. The La Cañada portions of the new community were also not as highly desirable as they have since become. Thus, at the time of cityhood, the fact that the Sagebrush area was not within the LCUSD was not a matter of unhappiness.
Efforts in 1991 and again in 1997 to try to change the district boundaries failed and it seems likely that they will fail again. The main reason is the Education Code, Sect. 35753(a), which does not allow a change of district lines to the extent that it promotes racial or ethnic discrimination or segregation, as well any which would cause a substantial negative fiscal result for the GUSD and which could be seen as primarily designed to increase property values.