How does Faulkner use symbolism to show the theme of old South versus new South, and what are some examples of this throughout the story?

The theme of change in the South after the Civil War is one of the strongest themes in the story. As such, there are numerous symbols of the old South and its fall from glory. First is Miss Emily herself. Growing up as an aristocrat immediately after the Civil War, she still represents the ideals of antebellum chivalry and aristocratic pride. When she is dealing with people who share her ideals, like Colonel Sartoris, there is little conflict; he merely remits her taxes after her father's death in order to spare her embarrassment. The conflicts between old and new come when "the next generation, with its more modern ideas, became mayors and aldermen" and Colonel Sartoris' solution "created some little dissatisfaction." After several attempts to contact Miss Emily through the mail, they come to her house to attempt to make her pay. Her formidable, proud, and dismissive attitude is emblematic of antebellum aristocracy and sufficiently intimidates the modern aldermen into giving up.

Another symbol of this clash between pre- and post-War South is Emily's house:

"It was a big, squarish frame house that had once been white, decorated with cupolas and spires and scrolled balconies in the heavily lightsome style of the seventies, set on what had once been our most select street. But garages and cotton gins had encroached and obliterated even the august names of that neighborhood; only Miss Emily's house was left, lifting its stubborn and coquettish decay above the cotton wagons and the gasoline pumps."

While Miss Emily's house is a symbol for the prestige the aristocracy of the South enjoyed in the past, it stands out in a neighborhood that has moved on to more modern establishments. These establishments "obliterated" the other houses like Emily's so that only hers remains.

Finally, the men in Miss Emily's life symbolize the past and future of the South. Emily's father, who is so proud that he thinks no man is good enough for her to marry, is a clear symbol of antebellum aristocracy. Old Tobe, her Negro servant who works for her well into old age, is a lingering symbol of the slavery that made the Grierson family so rich and successful. In direct opposition to these men (at least, to Emily's father), is Homer Barton, a working-class, Northern carpet-bagger who is in town to help "modernize" the area. Emily's choice to pursue him for marriage is a rebellion against her father and her past, but it is not one that is entirely successful and it does not seem that she is ready to fully give up an ideology that is so integral to her character. The elements of old and new South remain in conflict the entire time.