The New York Public Library's Irma and Paul Milstein Division of United States History, Local History and Genealogy boasts a collection of over 80,000 original photographs of New York taken between the 1870s and 1970. This site gathers many of those images together into a dynamic online map outfitted with red dots. Readers may zoom in, zoom out, and click on the dots to find photographs drawn from particular geographical locations, thereby witnessing the changing landscapes of New York City over a period of nearly a hundred years. For instance, clicking on the dot that corresponds to East 42nd Street and 2nd Avenue in Manhattan calls up over a dozen images from a number of decades, including a 1920 shot of the 3rd Avenue elevated train, which was eventually closed in the 1950s. Any photograph of interest can be explored in grater detail in the NYPL Digital Collections.