[Agent Carter] continued the color story from Captain America: The First Avenger. You’ll see Peggy in a lot of red, white and blue, as a silent tribute to her lost love, Captain America. Her trademark look is the red custom ladies Stetson Stratoliner hat, a burst of color in a sea of grey fedoras. Working in man’s world she needed to stand out, and she did that using color in her wardrobe.
—  Giovanna Ottobre-Melton, Costume Designer for Agent Carter (x)

Agent Carter’s signature blue suit, and her dramatic red hat (which Hayley [Atwell] noted is her favorite piece of her costume) are symbolic of Peggy’s role in society. Hayley added, “They add to the performance mainly physically, my posture and facial gestures reflecting the time: Up-right, put-together, proper, lady-like and hiding any true depth of feeling in order to be taken seriously in the work place.” (x)