There, the Children's Aid Society workers hoped, they would be adopted by families and put to work in fields and on farms. They were part of what is now known as the orphan train movement, a sweeping attempt to protect homeless, poor and orphaned children in a time before social welfare or foster care.

Families acted from various motives, and not all children who rode orphan trains found happy homes. Some suffered abuse, were treated like hired help or were never fully accepted. Officials knew that placing out was imperfect and did what they could to screen inappropriate families.

Kline's book is fictional, but it's based on the very true history of thousands of children shipped to the Midwest. Kline joins NPR's Rachel Martin to discuss the history of the trains, how young girls were often passed over by families and the most surprising fact she learned from train riders.

The Orphan Train movement illustrates the evolving concept of childhood in the 19th century. Placing out became the impetus for many Kansas child welfare laws and can be seen as a forerunner of today's foster care system.