Photographs, drawings and other images provide information you can't always get from a text source. Images can provide details of everyday life such as clothing and material culture. Though we often take photographs at face value. It is important to keep in mind that photographs are not an unbiased reflection of reality -- the photographer chooses what and how to depict a certain scene.
Many photographs do not provide much context, may not even provide an exact date or location. You will need to analyze photographs for clues. The example above shows the the Nickens general store located on the Coville Indian Reservation To date the photograph you may want to examine the car -- when was this type of cars made? Or perhaps search for the business name to find out when it existed.
Historic images of Native Americans reflect the stereotypes and prejudices of the period during which they were produced. Many reflect a romanticized vision of the American Indian. For some background information see the Bancroft Library exhibit Images of Native Americans.
Help: Making Sense of Documentary Photographs, Analyzing Photographs, Analyzing Material Culture, Learning to do Historical Research: Photographic Images.
For more information on images including citation and copyright see Finding and Using Digital Images.
Be sure to check the Indigenous Peoples: North America database which includes some newspapers, government documents, manuscript material & photos as well as American Indians of the Pacific Northwest which includes excerpts from the Annual Reports of the Commissioner of Indian Affairs to the Secretary of the Interior dealing with PNW tribes plus more than 2000 images. And also check the two databases currently on trial: American Indians and the American West, 1809-1971 & Early Encounters in North America.