A Line Dress - Definition of A-Line Silhouette
A-line dresses became popular in the 1960s. A range of fashion designers like Christian Dior and Pierre Cardin developed the A-line look. Dior sometimes created silhouettes that were different than mainstream fashion in his collections. The A-line coat below is from Dior's 1948 collection. At that time, it was unusual to see an A-line silhouette in clothing.
The A-line dress came into its own in the 1960s, with modernist designers like Pierre Cardin paving the way in pared-down minimalist styles, like the 1962 vintage coat seen with the designer at a fitting.
Sources: Christian Dior: The Early Years 1947-1957, Couture: The Great Designers by Caroline Rennolds Milbank