James M. Cain's The Postman Always Rings Twice was filmed in 1946 and directed by Tay Garnett for Metro-Goldwyn-Mayer after a long struggle to produce a script that could be filmed. The novel was considered controversial and erotic in its time. The film has toned down much of the erotic element. Both the novel and the film are set in a California, a California with a diverse but segregated and separated population. The state then was more rural than it is today, with large urban centers in San Francisco, Los Angeles, and to a lesser degree, San Diego. The setting for this film is not far from Los Angeles--the diner gets its produce from the market in Los Angeles, so the diner would be in the mountains outside the city, along the coast, somewhere in the Santa Monica mountains.
Ethnicity was certainly an important issue in California at that time and was manifested in a number of specific concerns raised by such actions as the Zoot Suit riots in the early 1940s, the internment of the Japanese in World War II, and the continuing influx of immigrants from various parts of the world. Hollywood, however, tended to homogenize its casting so that ethnic differences were minimized except for an accepted group of players who portrayed foreign roles in films requiring this. Ethnic differences emerge most often in family settings--the huge Italian family, or the Mexican family in a Western. In The Postman Always Rings Twice, ethnic differences have been all but eliminated so that only the most subtle differences can be discerned. This separates the world of the film from the real world of California, and form the point of view of the studio, Metro-Goldwyn-Mayer, it avoids controversy.
To understand the way ethnicity has been eliminated from the film, it is necessary to look back at the original material to see what was intended. The most obvious ethnic element in the original story by James M. Cain is the role of the husband, Ni...