When Lewis Hine began traveling the country in 1908 to document the working lives of children, around two million Americans younger than 15 were full-time laborers. A reformer and an investigative photographer for the National Child Labor Committee (NCLC), Hine, who trained as a sociologist, used his Graflex camera for what he called “detective work”: He’d materialize outside a factory or mine or cannery (sometimes in the guise of a Bible salesman) and wangle his way in. Other times, management denied him entry, even threatening him with physical violence.

I didn’t know that Hine was a trained sociologist when he started taking his camera into these places. How fascinating! The images are worth a look, they’re haunting and stark.