This is an art exhibit catalog to accompany Gary Reese's State of Change gallery exhibits, featuring selected film-based medium and large format rephotography of 155+ year old pictures of early Nevada. In this catalog, he provides a scholarly critique of Timothy O'Sullivan's photography from the King and Wheeler expeditions of 1867-68 and 1871. By having walked and rephotographed in O'Sullivan's tracks, Gary offers his informed insights on O'Sullivan's style as an artist and narrative documentary photographer. As an exhibiting art photographer, natural resources scientist and historic ecologist, Gary has found that presenting photomosaics of O'Sullivan's originals with his repeat photographs digitally blended into each view, can lead to enhanced engagement and appreciation by the viewing public. The book includes two appendices derived from interdisciplinary primary source research. Gary provides a complete record of the online imagery available from public archives, uniquely indexed by O'Sullivan's own field numbering. He also provides a vigorously researched time line, cross-referenced to letters, diaries and museum specimens produced by his co-workers, of where O'Sullivan photographed during the two government survey expeditions, correcting apparent errors in prior books on O'Sullivan's western expeditions.