In actuality, what makes waists appear smaller in paintings and photos is the illusion created by the dress styles, which in the 17th-18th centuries involved farthingales or panniers (above), in the 19th century involved wide crinolines or bustles (below), and in the 1940s involved padded shoulders. Long gowns with wide panniers or full skirts make the waist seem smaller in comparison, as does the triangular stomacher that narrows to a point just below the waist, like this one:
Studies of costumes at the Smithsonian, Colonial Williamsburg, and other museums provide the evidence. Curator Linda Baumgarten’s measurements of 18th-century stays and gowns show waist sizes ranging from about twenty-one to thirty-six inches. Author Juanita Leisch’s personal collection of garments from the Civil War era shows a median waist of around 23-25 inches. Scarlett O’Hara and her 18” waist aside, few women except teenagers (like Scarlett, who is 16 when the novel opens) had unusually small waist measurements.