There is something irresistible about before-and-after photographs, whether they document change that has occurred imperceptibly over many years or, as sometimes happens in fashion magazines, the transformation of a se afternoon. When the New York photographer Karen Maloof acquired a crate of about 170 glass-plate negatives in 1981 from a friend who had bought them at an Ohio auction, the box was marked “McCahon Studio, Newark, O.,” but the images themselves bore no identification whatever. Maloof decided to drive to Ohio and spend two weeks finding out as much as she could. She consulted area residents with reputations for long memories and persuaded the Newark Advocate to publish the pictures, asking readers for information. She also drove around trying to match the gingerbread on existing houses with the designs in her photographs. A McCahon tombstone in a graveyard turned out to be an important lead: cemetery records provided the name of a surviving relative who told Maloof that the studio had been run by a woman, Blanche McCahon. Still, at the end of two weeks, she had identified only six houses. Two return trips produced eighteen more identifications. Whenever she found a building still standing, she photographed it from the vantage point chosen by Blanche McCahon. Despite the vicissitudes of time, weather, fire, and the human urge to renovate and pull down, a few of the houses remain virtually unchanged, with descendants of the original owners proudly living in them.