Lewis Hine is perhaps my favorite photographer; a Columbia University sociologist converted to photography, he captured influential photos at Ellis Island and in the US child labor industry. His work served to document history, but, more importantly, it worked to bring about social justice. While statistics, surveys, and case studies are an important part of passing legislation, Hine offered the greatest factor through his photography by appealing to human empathy.
This image of "breaker boys" in 1910 helped influence changes in youth labor legislation early in the 20th century in America. In it, Hine captures a group of young boys who separate coal from slate daily in South Pittston, Pennsylvania.