Scope and Contents Greeting and holiday cards gained popularity in the early 1900s when stamps became more available to all social classes. Valentines are some of the oldest forms of holiday cards, and are typically more intricate and detailed because of the importance attached to the Valentine holiday. Postcards became one of the most popular and easiest types of cards to send in the mail during this period.This collection contains a variety of Valentine, holiday, and greeting cards, in postcard...