It's optional I suppose. I'm not aware of any official city documents that use it, but it has historical roots.
> California Governor Felipe de Neve established the first civilian town or pueblo in California on November 29, 1777. Founded near the southern end of San Francisco Bay, it was christened El Pueblo de San José de Guadalupe.
[1] http://web.archive.org/web/20080218051828/http://www.califor...