Even though Palmdale is in Los Angeles County , it is not connected to the larger Los Angeles population area . It is separated from it by a mountain range called the San Gabriel Mountains that are over 40 miles wide and almost 2 miles high overall . While Palmdale is still a part of Los Angeles County , the urbanized centers of Palmdale and Los Angeles are separated by the San Gabriel mountain range , which is about 40 miles ( 60 km ) wide .