It happened around 8:30 Friday morning at the Trenton Procession Plant on Klockner Road and Route 130 in New Jersey.
The alligator, which was less than 12 inches long, had apparently escaped from its packaging.
The animal was secured without incident and no injuries were reported.
Officials with U.S.P.S. contacted the intended recipient who picked up the alligator later that afternoon.
The person who mailed the animal was also contacted.
Authorities say it is legal to mail live animals and reptiles as long as strict guidelines are followed.
