Jonathan Zimmerman teaches history at New York University and lives in Narberth. He is the author of “Small Wonder: The Little Red Schoolhouse in History and Memory” (Yale University Press). He can be reached at jlzimm@aol.com.

In 1979, 6-year-old Etan Patz disappeared on his way to school in New York. Last month, a fruitless search for Patz’s remains in a SoHo basement prompted a national wave of nostalgia for the innocent days of yore. For most of our history, we told ourselves, kids were safe. Then we lost Etan.

But we lost our innocence long before, with the 1874 kidnapping of 4-year-old Charley Ross right here in Philadelphia. That was when Americans discovered they could never keep their children completely safe. And we’ve been living with the consequences ever since....

Fifty years later, when Richard Loeb and Nathan Leopold were arrested for abducting and murdering 14-year-old Bobby Franks in Chicago, a member of their defense team reported that Loeb had been inspired by “a crime that nobody could ever detect” — the kidnapping of Charley Ross. Eight years after that, when the aviator Charles Lindbergh’s infant son was abducted and killed, one newspaper ran reward posters for Charles Lindbergh Jr. and Charley Ross side by side.

“The men and women who were children in the days of the Charley Ross kidnapping can remember how their mothers warned them to stay in the house, never talk to strangers, and regard every old clothes man as a potential ogre who would carry them off and strangle them and cut them into little pieces,” the New Republic editorialized in 1932, a few days after the Lindbergh baby was found dead. “The Lindbergh case is likely to produce an even wider reaction.”...