AMANDA UREN, MASHABLE:
"Like the vast majority of erotic postcards from the late nineteenth and early twentieth century, these were made in France. Such cards came to be known informally as 'French Postcards' in the U.S.
"However, such postcards were actually illegal to send via mail carrier in the U.S. Thus, they were traded very discreetly in stores and by French street traders.
"Creating erotic images could be a lucrative sideline for early photographers, who would use a false signature to avoid tarnishing their professional reputation and encountering problems with the law.
"The identity of almost all 'French Postcard' models remains entirely unknown."
Take a look at these "erotic postcards" from the past. Click here.