Travilla's version of the sack back dress from 1958. The dress is likely fitted to the body under the blouson that falls from the thin shoulder straps and tucks back in under the waistband. The magazine calls this a "cocktails-through-dawn" dress. I like that description. Sold for $125 in 1958 (about $1,007 in today's dollar.)
Photo by Louise Dahl-Wolfe for Harper's Bazaar.