What is the theme of "The Lottery" and what true events mirror the central action of the story?

Jackson's "The Lottery" is very much a scapegoat story
that reflects the terrible behavior and cruelty humans are capable of when that behavior
is sanctioned by one's neighbors, by the majority.

The
story most directly suggests pogroms to me, events that were common in Europe before and
during WWII.  The Nazis weren't the only ones who killed Jews, Gypsies, and homosexuals
during WWII.  Anti-semitism was common in Europe.  A pogrom is a spontaneous uprising
against a minority, rather than a big-government master plan to eliminate a minority. 
It is a kind of riot against one's neighbors who are different from oneself.  Cruel acts
are invariably performed by individuals seemingly not willing or capable of performing
these acts on their own.  Joined to a mob, however, the mob mentality prevails and
persecution results--the scapegoats are eliminated, as in "The Lottery."  The minority
suffers at the pleasure of the majority, for the sake, it is thought, of the
majority.