You can limit your Google image search to those images that can be freely used. Once you have done your search, click on the "Tools" button on the right below the search box. Select "Usage Rights" and then "Creative Commons Licenses."
While all Creative Commons Licenses allow for reusers to copy and distribute the material in any medium or format, there are multiple levels of the license. These are described in About CC Licenses
The Library of Congress site offers access to more than 9 million digital items from more than 100 historical collections of primary source materials relating to the history and culture of the United States. The collections include manuscripts, photographs, posters, maps, books, pamphlets, and sheet music, as well as sound recordings and motion pictures and can either be browsed or searched.
Detailed descriptions of primary resource collections maintained by more than 200 contributing institutions including libraries, special collections, archives, historical societies, and museums throughout California and collections maintained by the 10 University of California (UC) campuses.
A digital image library of over 2 million images in the areas of art, architecture, the humanities, and social sciences. Registering for a personal account will allow you to download images, save images into groups, share your groups with other Artstor users, view groups created by other users (such as collections set up by course instructors), add notes to individual images, set personal display options, and export citations. Rutgers-restricted Access
A large collection of historical photographs contributed by over 100 cultural institutions in 24 countries around the world. Images have no known copyright restrictions.
Search or browse over 7,000 advertisements printed in U.S. and Canadian newspapers and magazines between 1911 and 1955.
Covers five main subject areas: Radio, Television, Transportation, Beauty and Hygiene, and World War II. A project of the Digital Scriptorium,
Rare Book, Manuscript, and Special Collections Library, Duke University.
Over 9,000 images relating to the early history of advertising in
the U.S. From collections in the John W. Hartman Center for Sales,
Advertising &
Marketing History at Duke University.