San Francisco. For whatever reason, a lot of Asians like to wear masks (I don't know why), and there are a lot of Americans of Asian descent in San Francisco. And, of course, Leftists wear the mask as a religious talisman - to show that they are a member of the Leftist tribe. And, also of course, there are many Leftists in San Francisco ... so, it would lose the public vote in most places - but I doubt it would lose in the San Francisco Bay Area.
You just contradicted yourself. If everyone in SanFran wears masks then why have a mandate?