Fortunately there is a little information to be found online, and his photos by the dozen are available, too.
There is also an interesting book for children by Elizabeth Winthrop called Counting on Grace.
1910. Pownal, Vermont. At 12, Grace and her best friend Arthur must leave school and go to work as a "doffers" on their mothers’ looms in the mill. Grace’s mother is the best worker, fast and powerful, and Grace desperately wants to help her. But she’s left handed and doffing is a right-handed job. Grace’s every mistake costs her mother, and the family. She only feels capable on Sundays, when she and Arthur receive special lessons from their teacher. Together they write a secret letter to the Child Labor Board about underage children working in Pownal. A few weeks later a man with a camera shows up. It is the famous reformer Lewis Hine, undercover, collecting evidence for the Child Labor Board. Grace’s brief acquaintance with Hine and the photos he takes of her are a gift that changes her sense of herself, her future, and her family’s future.For kids this is an eye-opening novel in that is makes real the life of a poor mill girl in the early part of the 20th century, and, introduces them to how Lewis Hine worked. I listened to the book on audio [J AB/CD WIN] and found it quite compelling. A bonus for listeners is to hear the writer talk about the photograph that inspired the story. She also includes background information about Hine.
Library of Congress description: [Addie Card], anaemic little spinner in North Pownal Cotton Mill.
In doing an online search I found the Lewis Hine Project which was started by Joseph Manning. Manning was hired by Elizabeth Winthrop, author of Counting on Grace, to research the background of the child, Addie Card, whose photo set Winthrop's book in motion. Manning is now researching many of the children whose photos were snapped by Hine one hundred years ago! (Addie Card's picture was taken in August, 1910!)