When it absolutely, positively has to get there ... sometime

The Smithsonian has made available on Flickr an archive of old photos, which you can view here.

Here's a photo from the archive with an interesting story. It seems that after the US Postal Service began offering parcel post service, a couple of, uh, enterprising parents decided to ship their young ones that way ("hey kids, want to go visit grandma?"):

Description: This city letter carrier posed for a humorous photograph with a young boy in his mailbag. After parcel post service was introduced in 1913, at least two children were sent by the service. With stamps attached to their clothing, the children rode with railway and city carriers to their destination. The Postmaster General quickly issued a regulation forbidding the sending of children in the mail after hearing of those examples. [emphasis added]

I guess you have to use UPS or FedEx now. :)