This catalogue accompanies a traveling exhibition organized by the National Gallery of Art, Washington, highlighting the chronological progression of photographer Harry Callahan's career. It traces his artistic development from Detroit in the early 1940s, through his influential years in Chicago during the late 1940s and 1950s, to his later work in Providence and Atlanta. Instead of organizing his photographs by subject, this exhibition tracks the evolution of his visual style over time. An essay by Sarah Greenough provides insights into Callahan's artistic vision, offering context to his innovative approach to photography.