x
 



An interesting write-up on Dust Jackets can be found in Wikipedia,
following is an exerpt:

After 1900, fashions in, and the economics of, publishingcaused book bindings to become less decorative, and it was cheaper for publishers to make the jackets more attractive. By around 1920, most of the artwork and decoration had migrated from the binding to the dust jacket, and jackets were routinely printed with multiple colors, extensive advertising and blurbs; even the underside of the jacket was now sometimes used for advertising.

As dust jackets became more attractive than the bindings, more people began to keep the jackets on their books, at least until they became soiled, torn, or worn out. One bit of evidence that indicates when jackets became saved objects is the movement of the printed price from the spine of the jacket to a corner of one of the flaps. This also occurred in the 1910s and early 1920s. When jackets were routinely discarded at point of purchase, it didn't matter where the price was printed (and many early jackets were not printed with any price), but now if book buyers of the 1910s and 1920s wanted to save the jacket and give a book as a gift, they could clip off the price without ruining the jacket.
Prices for dust jackets have become so inflated in recent years that even early reprints of certain titles in jacket can command good prices.