"A Streetcar Named Desire" is set in the tenement slums of New Orleans. The drab, urban setting provides the backdrop against which the internal dynamics involving Blanch, Stella and Stanley take place. Blanch and Stella, we are to understand, are from a more upper-scale social, economic and rural background, specifically, the plantation world of Mississippi. Stanley is a product of the desperately lower-income city. The introduction of Stella, an alcoholic former English teacher whose career ended when she was discovered to have engaged in an affair with a student, provides the tension that grows to its violent and sad climax with her rape by Stanley, the downtrodden factory worker.
The title of the play refers, of course, to the streetcar route that runs through the part of the city where the characters live. It adds to the depressed urban atmosphere in which the story takes place.
That southern locales were employed in the play simply illuminates Tennessee Williams' origins and the strong cultural connection he maintained to the South throughout his writings.