Today I saw the following photo (funny: on a russian blog)
and found it really captivating, more so than the classic photo of Sharbat Gula (the 'Afghan Girl' on the NGS magazine cover).
And digging a little deeper, there's quite a lot of story here: the photographer, Lewis Hine did some remarkable work on child labour in the USA before WW1 - only to be shunned later on, and to die in poverty.
Eventually I found larger versions of this photo at the Library of Congress together with the original caption:
One of the spinners in Whitnel Cotton Mfg. Co. N.C. She was 51 inches high. Had been in mill 1 year. Some at night. Runs 4 sides, 48 cents a day. When asked how old, she hesitated, then said "I don't remember." Then confidentially, "I'm not old enough to work, but I do just the same." Out of 50 employees, ten children about her size. (Dec 1908)
Most of these photos and their subjects would be forgotten today if it weren't for Joe Manning who dug up lots of history on many of these kids' later life - amongst others, the story of Cora Lee Griffin.