In 1958, [[American Airlines]] revolutionized the air cargo business by developing a container that could be carried on aircraft minimizing the loading and unloading time. For some reason, they called it the Paul Bunyan Box.
Today, hundreds of thousands of these containers are used by every airline in the world. Specialized material handling equipment rolls them on and off and baggage or cargo can be handled quickly and efficiently. Barcoding allows them to be tracked anywhere in the world and some modern airports and cargo facilities have automatic routing equipment.
This plate probably dates back to 1958 and shows quite a bit of wear. An interesting find.