Robert Camacho, who has lived in Bushwick, Brooklyn, most of his life, used to be able to point to a home in his neighborhood and say who resided there. Now he struggles to find a familiar face on his own block.

The row of modest, two-family homes across from his house on Stanhope Street was replaced two years ago with a 26-unit condominium building. Bushwick Avenue, a nearby residential corridor that Mr. Camacho said was once lined with children walking with their parents after school, is now empty in the midafternoon,...