Fascinating new book Real Photo Postcards: Pictures of a Changing Nation is out in May and published by the Museum of Fine Arts, Boston. It's revealed that 'real photo postcards' became 'omnipresent' in small towns and large cities across the United States around the turn of the 20th century thanks to leaps in photography technology by the Eastman Kodak Company, which introduced a portable camera that produced a postcard-sized negative that could print directly onto a blank card lined with photo-sensitive paper. The book explains: 'Postcard photographers documented scenes worthy of Walt Whitman and seldom, if ever, recorded in other photographic formats. Photo postcards reach across time and history to convey powerful stories about real people, the conditions of their lives, their talents and vocations, their dignity, their cultural identities, and the hopes and aspirations they may have held.'