Republican presidential candidate Newt Gingrich turned a few heads in November when he called U.S. child-labor laws "truly stupid." The former House speaker said having kids from poor homes take a turn as school janitors would teach them a work ethic they're not learning at home.

Everyone from union representatives to child advocates to social scientists expressed outrage over the idea.

But child labor -- in jobs far more demanding and dangerous than custodial work -- was once the norm in America. Bringing the practice to an end took years of political and cultural pressure. And it required overcoming opposition from businesses, parents and even children themselves.

Gingrich and his critics probably didn't realize that the country is approaching the 100th anniversary of the founding of the U.S. Children's Bureau, the first federal agency empowered to look at child-labor issues. Congress created the bureau in 1912, after years of prodding by Progressives, who thought American children should be in schools and not in factories, mines and mills.

But tougher child-labor laws were also, in large part, the work of one photographer: Lewis Hine.

You might not recognize the name, but you've probably seen Hine's iconic images: a lone girl surrounded by cotton-spinning machines in the South; "newsies" as young as 5 peddling papers on city streets; coal-dust encrusted "breaker boys," who risked injury -- and sometimes death -- sorting through Pennsylvania anthracite.

As memorable as the pictures are, Hine was more than a photographer. He saw himself as a researcher and social reformer, and he interviewed the children he photographed. His captions gave an extra punch as he detailed the lives of these children in and out of the workplace.

"The picture is a symbol that brings one immediately into close touch with reality," Hine said in 1909. "The picture continues to tell a story packed into the most condensed and vital form." He hoped his photos would make "the whole country so sick and tired of the whole business" of child labor that lawmakers would finally end it.

From 1908 to 1924, Hine took photographs for the National Child Labor Committee, a private organization that was then leading the charge against child labor. He crisscrossed the country, covering some 100,000 miles and taking about 5,000 photos.

He worked undercover, since most mine owners and mill operators didn't want him, or anyone else, documenting children at work. At times he said he was a fire inspector or a salesman, and he learned how to surreptitiously take notes on a pad he kept in his pocket. When he did present himself as a curious photographer, Hine told company owners he merely wanted to shoot their machinery. He waved a child or two into the photo, he said, to show the scale of the equipment.

The Progressives faced several obstacles in their struggle against child labor. Children had worked alongside their parents for thousands of years on farms and in households, and as the Industrial Revolution took off, they went to work in factories, as well.

Mill and mine owners had an entrenched interest in youth labor. They could pay children less than adults, and kids wouldn't join unions or strike to protest dangerous working conditions. And the owners insisted that certain jobs required the nimble fingers of the young. Samuel Slater, who built the first U.S. textile mills in Rhode Island, used children as young as 7 to operate his spinning machines.

States often helped businesses by ignoring whatever child-labor statutes might have been on the books. Pennsylvania law, for example, said boys had to be at least 14 to work in the mines or 12 to work in a colliery. Parents, who welcomed the extra income that children brought in, produced forged documents, and mine owners looked the other way.

Finally, to many kids, work -- even dangerous work -- was a welcome alternative to school. Hine, a former teacher, couldn't believe the stated ages of some of the boys he met at the Pennsylvania collieries. Equally appalling was their lack of education. One boy who claimed to be 12 couldn't write his own name.

Hine's photos, and the dogged efforts of Progressives, led to the creation of the Children's Bureau, but they didn't completely end child labor. The true demise came during the New Deal with the passage of the Fair Labor Standards Act of 1938. The law said children under 16 couldn't work in most jobs.

Since then, most Americans have seemed content to keep the majority of kids in school and out of the workplace. Hine's photographs remain a haunting reminder of the drudgery and dangers that too many American children faced while going without schooling -- no matter how honed their work ethic might have been.

(Michael Burgan is the author of "Breaker Boys: How a Photograph Helped End Child Labor Laws." The opinions expressed are his own.)

To contact the writer of this post: Michael Burgan at mburgan@yahoo.com

To contact the editor responsible for this post: Timothy Lavin at tlavin1@bloomberg.net