How is the theme of identity explored in Tennessee Williams' play 'A Streetcar Named Desire'?

Williams explores identity primarily through the mental deterioration of the character 'Blanche' and her struggle to shed the life of the 'Southern Belle' and become a part of the Post-WW2, modern society. Blanche's conflict of identity can be seen in Williams' use of costume as she morphs from being dressed "daintily in white" to wearing a the 'Scarlet robe' in the final scenes of the play. Both outfits present to the audience a drastic change in identity, although neither allow her to fit into the working-class background where she lives, where men wear "denim" instead of elegant furs. It could even be said that Blanche's wardrobe reflects her inability to leave behind her past life at 'Belle Reve' as she continues to dress as though she was part of the upper-class, despite her family having lost it all. Ultimately, it is Blanche's inability to escape her identity as the 'Southern Belle' which leads to her downfall in the staggeringly contrasting city of New Orleans.