According to City-Data.com, Northwest Hills district consists of 14 neighborhoods. This includes Montclair Village, one of the original "artist colonies" of the Bay Area. The mainly steep, hilly terrain spread out over a wide geographic area lends itself to a less dense population as there are many uninhabitable areas.
This is a nice area of Oakland which has a broad socio-economic cross section of people from all walks of life including, but not limited to teachers, librarians, historians, attorneys, small business owners, retirees, young families with children, etc.
In 2010 the Northwest Hills district had an approximate population of 27,120, with the majority living in the Upper Rockridge, Claremont, Montclair, Oakmore, and Piedmont Pines neighborhoods.