The photographs of William Henry Jackson taken during the 1871 survey of the Yellowstone region of Wyoming and Montana have often been cited as the first specific group of photographs used for successful persuasion. Many historians credit Jackson's photographs as being the most influential factor in persuading Congress to designate the Yellowstone region as the nation's first national park. But a closer examination of historical reports and congressional accounts shows that these claims are exaggerated. Oral descriptions of the area from unofficial expeditions prior to the survey sounded unbelievable, but were consistent in many ways, thus lending the stories credibility before the Jackson photographs were taken. An article from a prominent newspaper applauding passage of the national park bill made no reference to the Jackson photographs. Jackson himself viewed his role as expedition photographer as supportive rather than primary. Although congressional members received the photographs as part of the Yellowstone lobbying effort, those members most influential in the passage of the bill were more likely persuaded by accounts from family members in previous expeditions than by the photographs. There is little evidence that Jackson's photographs were more influential than the reports and specimens presented to Congress in persuading members to designate the area a park. (HTH)