Hammond printed these three unique, regional maps of New York City, Boston, and Philadelphia in its 1910 New Reference Atlas of the World. All three are copyrighted before 1910, so they might also have been published in earlier atlases. Together, the maps offer a nice snapshot of development across three major Eastern regions at the end of the Victorian period, and just before cars really began to influence urban land use patterns. (Note the railroads.) These are the only three maps from Hammond’s regional series that I’ve been able to find. Would be nice to see others if they’re out there. (Chicago? San Francisco?) Maps of American states and cities-proper, from the same atlas, can be found at the US Digital Map Library.