Occupy SF
Occupy SF is a movement based in San Francisco, California that is part of a broader global Occupy movement "which is primarily directed against economic and social inequality"*.
These photographs were taken in October 2011 at the Occupy SF camp in Justin Herman Plaza and at a smaller camp on Market Street.
You can read more about the Occupy SF protest on their web page.
Dave Dunne October 2011
*Description from Wikipedia.