"In 1913 it was legal to mail children. With stamps attached to their clothing, children rode trains to their destinations, accompanied by letter carriers. One newspaper reported it cost fifty-three cents for parents to mail their daughter to her grandparents for a family visit. As news stories and photos popped up around the country, it didn't take long to get a law on the books making it illegal to send children through the mail."
With thanks to Thomas Doty.