It’s been a lot of fun (and a fair amount of work) compiling these lists, but I think it provides an interesting “snapshot” if you will of the time period and the cultural impact of photography. Looking at the Washington DC map, there are almost as many studios as there are in Philadelphia in the same time period, yet aside from the government, DC was a sleepy little glamor-less town of 50,000 or so nobodies at the time of the civil war, whereas New York and Philadelphia were the two largest, most cosmopolitan cities in the US at the time (although I’m sure Bostonians would argue the latter point).
dcphotoartist 
Wonderful resource! Thanks!
It’s been a lot of fun (and a fair amount of work) compiling these lists, but I think it provides an interesting “snapshot” if you will of the time period and the cultural impact of photography. Looking at the Washington DC map, there are almost as many studios as there are in Philadelphia in the same time period, yet aside from the government, DC was a sleepy little glamor-less town of 50,000 or so nobodies at the time of the civil war, whereas New York and Philadelphia were the two largest, most cosmopolitan cities in the US at the time (although I’m sure Bostonians would argue the latter point).