At the Crossroads of American Photography examines the aesthetic and personal interrelationships of three photographers who helped define the course of American photography after Steiglitz: Frederick Sommer (1905-1999), Harry Callahan (1912-1999) and Aaron Siskind (1903-1991). Although each member of this holy trinity (as they were dubbed by photographer and publisher Jonathan Williams) has been honored with individual museum retrospectives, this is the first full comparison of their work, as well as an exploration of their robust, prescient exchange of ideas about photography, abstraction and metaphor over the course of their 25 years as colleagues and friends. Self-taught as photographers, this trio helped shape a national community of peers and the evolution of photography as an art form, creating a bridge between the purity of Group f/64-era photography at midcentury and the hybrid approaches to the medium seen today. This exquisitely produced exhibition catalogue highlights the powerful role of such camaraderie in shaping photography at this seminal time, before the emergence of a market for photography and before widespread artistic acceptance of the medium. It brings to light contrasting philosophies of the artist/photographer’s role (influenced by Existentialism for Siskind and by the writings of Spinoza for Sommer), the interest in chance as an artistic process, the expressive potential of photographic found objects and collage, experimental abstraction, close affiliations with fine art movements (New Bauhaus, Abstract Expressionism and Surrealism), and changing attitudes toward the fine-print tradition.