Popular Graphic Arts Collection from the Library of Congress (c. 1835- 1900)
"About 15,000 historical prints (ca. 1700-1900) created to document geographic locations or popular subjects and sometimes used for advertising and educational purposes. Most are by American printmakers (e.g., Baillie, Currier & Ives, Sachse & Co.), but publishers in many other countries are also represented (e.g., Antonio Vanegas Arroyo). Subjects vary widely, from city and harbor views, street scenes, and manufacturing plants to genre scenes, historical events, religious iconography and portraits."
To find advertisements, you can do keyword searching or browse images by subject (here: http://www.loc.gov/pictures/collection/pga/index/subjects/ ) Most ads are indexed under "advertisements," but some are also indexed under the products they advertise.