Postcards have been sold by the billions over the past 100 years or so, but you never would recognize their popularity by checking library holdings. Most libraries ignore them, yet a reporter observed at the 1981 national poster and postcard show: “Postcard collection—a nostalgic pastime that has become a consuming passion for thousands of Americans—is more popular today than when picture postcards first caught on at the turn of the century.” Among the dealers of new cards, Kennard Harris says that “in the past five years there has been an explosion of museum postcard publishing and sales in this country.”