Hillsborough is an incorporated town in San Mateo County, California. Hillsborough is one of the wealthiest places in America and has the highest income of places in America. It is south of San Francisco. The town is served by Hillsborough City School District. There are no apartments, condominiums or townhouses in the city limits; however, it is not unusual for multi-million dollar mansions along the eastern edge of Hillsborough to face condominiums in neighboring Burlingame, with which it shares ZIP code 94010.