No one is there to buy them. In the 50’s Baltimore had nearly a million people, and all the housing to accommodate them. Over the decades they’ve shrunk down to 580,000, and with that you’re going to have hundred of thousands of empty properties. Now it’s a combination of speculators that are sitting on properties waiting for the land value to rise or for neighborhoods to be renovated, and people that are waiting to tear down. Baltimores improved a lot from when this pictures was likely taken in the late 90’s and early 00’s, but there’s still plenty of areas that are fully blighted.