Elite American women embraced the pastoral look that was popular in France in the late 1700s. At the turn of the century (1700 - 1800), American women wore the Empire style with its high waist and somewhat flimsy fabric but in a more modest manner. You can find out more about how women in the United States of America dressed during that time by reading some books including:
"The Encyclopedia of World Dress and Fashion Volume 3 United States and Canada" by Phyliss G. Tortora
"Historic Dress in America 1800 - 1870 Part 2 History of Fashion Book 18" by Elizabeth McClean
Also, take a look at the Colonial Williamsburg site. You can search the Metropolitan Museum of Art's Costume Institute online. They even have at least one picture of a beautiful dress of that era. Also American Heritage Magazine online features "We Wore What We Wore," published Dec. 1988, Volume 39, Issue 8.
Check out the website called Historic New England. The group maintains a clothing collection that you can investigate online. I am sure you can contact them for information.