At the turn of the last century, the photographic postcard became a new and inexpensive means of communicating. Photographers could print their own photographs on special postcard-sized paper, write a short message on the other side, and send it through the post.
Photo by Mike Yoder
1920 Photo postcard. Postcard reads "This is the whale I saw at Port Arthur in March. I have put the measurements on it as given by the state biologist from the T.S.U. at Austin. Letter tonight. C.H.R."