In the early years of Parcel Post service, before the U.S. Post Office implemented more specific regulations, people shipped all sorts of unusual things by mail — including babies and small children.

Not that it was a usual occurrence, and was most often a way of listing children as “mail” so as to avoid the cost of a train ticket or similar purposes.

Inquiries could be humorous:

Fort McPherson, Ga.
Postmaster General,

Washington, D.C. — Sir: I have been corresponding with a party in Pa about getting a baby to rais (our home being without One.) May I ask you what specifications to use in wrapping so it (baby) would comply with regulations and be allowed shipment by parcel post as the express co are to rough in handling.

This wasn’t entirely enforced, however. Two weeks after this, a mail carrier in Ohio delivered a baby from his parents to his grandmother:

“Vernon O. Lytle, mail carrier on rural route No. 5, is the first man to accept and deliver under parcel post conditions a live baby. The baby, a boy weighing 10-3/4 pounds, just within the 11 pound weight limit, is the child of Mr. and Mrs. Jesse Beagle of Glen Este. The boy was well wrapped and ready for ‘mailing’ when the carrier received him to-day. Mr. Lytle delivered the boy safely at the address on the card attached, that of the boy’s grandmother, Mrs. Louis Beagle, who lives about a mile distant. The postage was fifteen cents and the parcel was insured for $50.”

Images above vintage postcards to poke fun at the institution.
Via Snopes.