Scout's overalls symbolize her freedom from feminine constraints in Southern society and her desire to be a tomboy. Atticus supports her in being herself and developing her own personality in her desire to wear these boyish clothes, even if they cut against social convention.
In contrast, at the end of the novel, the ham Scout has to don for the Halloween pageant foreshadows her entrance into a more constricting world of traditional feminine dress, and symbolizes how gender in her society will hamper and endanger her.
The costume, with its chicken wire mesh frame, is similar to a hoop skirt. Scout comments wryly that the person who made it, Mrs. Crenshaw, had the thoughtfulness to put in eyeholes so Scout could see.
When she is being pursued by Ewell, the costume constrains her. When the attack comes, Scout says she was
floundering to escape my wire prison.
It is significant that the pageant and costume are the brainchild of Mrs. Merriweather, who thinks the idea of dressing the children up...
(The entire section contains 3 answers and 524 words.)