Hillsdale is a populated place LOCATED WITHIN the City of El Cajon. In turn, the City of El Cajon is located within San Diego County.
Hillsdale is located at latitude 32.779 and longitude -116.928.
Since Hillsdale is located within the City of El Cajon, all of the census and demographic data for residents of Hillsdale are included as part of the information reported for City of El Cajon in the "Profile" tab above.