Much more than simply the southern half of
California. Southern California is the
idea of a place which is noted for its
smog, rampant
urban sprawl, and a
news media more concerned with
police chases and
celebrity weddings than things that matter. It is defined, of course, by
Los Angeles.
Northern Californians have been know to refer to it as the evil empire while muttering things about water.
(Of course, these might just be the rantings of someone who is convinced the place was killing him.)