I’m trying to track down images of key historical figures from U.S.
history and I just found this site from the Library of Congress which
lists peoples across the different collections.
But I have to be honest here and admit that one of the best tools
I’ve found recently is Wikipedia (which does track sources of most
uploaded photos). Ironically many of them ARE from the Library of Congress, but sometimes using Wikipedia is actually slightly more efficient than trying to navigate the LOC.