HIST: U.S. Immigration project

The sites below are enormous, digital depositories.  Browsing is usually difficult, so your best bet is to use the search function.

• Calisphere, University of California's digital primary sources
  The University of California's free public gateway to a world of primary sources— including photographs, documents, newspaper pages, political cartoons, works of art, diaries, transcribed oral histories, advertising, and other unique cultural artifacts.
• New York Public Library Digital Gallery
  Provides free and open access to over 800,000 images digitized from the The New York Public Library's vast collections, including illuminated manuscripts, historical maps, vintage posters, rare prints, photographs and more.

Google is a great resource for images, but make sure you have permission to use images!