I think this is really interesting. Among the thousands of iconic and easily recognizable photographs of segregated water fountains in the American South, you will almost never find one that features a black woman, a white woman or a white man drinking. They are nearly all of black men drinking. Why is that?
In her fine and thoughtful book Signs of the Times: The Visual Politics of Jim Crow (University of California Press, 2010), Elizabeth Abel tells us why. Segregation, like many social phenomena, had a triple life. 1) It was a thing, part of an objective reality now past (one wants to cite Ranke here). 2) It was a thing seen, an object filtered through the subjective experience of viewers (one wants to cite Kant here). 3) And it was a thing shown, a sign made by one person to be communicated to others (one wants to cite Saussure here). We can see these three lives in the sources Abel examines: photographs of segregation signs: "Whites Only", "No Negroes", "Colored Entrance", and so on. They simultaneously tell us about the way segregation actually worked (Ranke), the way participants observed it (Kant), and the way photographers tried to show it to their audiences (Saussure). Able analyses all three lives, but her focus--and the explanation for the black-man-at-a-water-fountain photographic cliché--is really to be found in her investigation of the third. The photographers, most of whom were white liberal northerners, framed the depictions of the signs so as to convince spectators that segregation was degrading to blacks. Thus they usually moved whites completely out of the frame. Moreover, they elected to focus attention on the subject who could be most humiliated because that subject had, relatively speaking, the most status. So black men (high status) were shown rather than black women (low status).
This example is only one of Abel's many fine readings of these photographs. There are many others. I encourage you to pick up the book and see for yourself.
Available at: http://works.bepress.com/marshall_poe/290/