Of course, you can get historical photos from the Library of Congress, but this is another source.
The web site is an archive of photos covering more than 200 years of American history. In fact, it takes you all the way back to the early 1600s. It is possible to browse the images through categories called, category, decade and photographer.
Category has the topics of: Abraham Lincoln; Architecture & Buildings; Arts & Entertainment; Business & Commerce; Historic Eras and Events; Law & Criminal Justice System; Life Cycle; Nature; People & Professions; Places & Vistas; Politics & Government; Science; Health & Medicine; Social Conditions and Trends; Transportation & Communication; and War & Military.
Photographers are: Edward Anthony; George N Barnard; Mathey Brady; Charles D. Fredricks; Jeremiah Gurney; Alexander Gardner; Lewis Hine; William Roe Howell; Dorothea Lange; Jose Maria Mora; Timothy O’Sullivan; Jacob Riis; Napoleon Sarony and William Shaw Warren. (Brady is the only one I know.)
The Anniversary one is really fun, because it gives dates by month and associates a photo with that date. For example, January 1, 1892 was the opening of the Ellis Island Immigrant Station. So they have a picture of the station.
The only issue that I might have with this site is that the pictures are watermarked and are limited to 300 dpi. Licensing rates depend on usage and length of time in use.
See it all here: http://www.picturehistory.com
