The Bureau of Land Management has a site which houses Historical Pictures from the 1890s to the 1980s. You can browse or search the collection. Many pictures are considered in the public domain,.
For those interested in the United States and its history, this collection gives you a glimpse back. In its introduction the BLM Historical Pictures site says:
The historical database contains more than 3,500 historical digital images, some dating back more than a century. These images document the nation’s westward migration and highlight the activities of the General Land Office and the Grazing Service, which were later consolidated to form the BLM. The photos in this database are part of BLM’s digital photo library.Definitely worth a look or two.....and many more!