Fashion in 1883 was dependent (as is always the case) on geographic location, economic status, ethnicity, religion and a range of other factors. Most of the available images (photographs and paintings) represent wealthy or well-to-do women who could pay for (and pay attention to) fashion. Most female characters in The Gilded Hour are artists, teachers, housewives, nurses and physicians; the primary characters are advocates of the rational dress movement of the period, which rejected narrow styles, corsets and bustles as restrictive and unhealthy.
The clothes Anna and Sophie wear are fictional, but based on 19th century artistic and aesthetic dress, the early (and failed) Bloomer movement, and the tea gown. Split skirts as described in the novel were on the horizon, and became reality with the increasing popularity of the bicycle.
This example of a tea gown (Liberty & Co. ca 1890) provided a loose basic model for the fashions described in the novel.
For comparison’s sake, examples of highly fashionable dress, requiring tight corseting.
Dark blue cotton (faded) with small white dot. Bodice lined with white cotton. CF fastening with five bone buttons. Low standing collar and waistband. Long sleeves. Much worn, altered and mended.
While the next painting is of farm people in Sweden, the general style would be relevant to Americans who lived in rural areas in the 1880s.