Serial numbers and dating

How come the shipping date indicated by the serial number doesn’t always match the date given in Gibson’s ledgers? Below, Joe Spann explains:

“The answer is very simple. While the serial number would normally indicate the instrument’s first shipping, there are several reasons why the shipping of a Gibson instrument might be delayed.

1. The earliest shipping date (or dates) may simply not be recorded in the shipping ledgers. The ledgers are notoriously unreliable and full of errors and omissions. Many high-cost instruments were shipped and returned over and over again. The date recorded in the ledgers might be a second, third, or fourth repetition of shipping.

2. The guitar was completed on the date indicated by the serial number but was then purchased directly at the factory thus requiring no shipping ledger entry. It was later returned to the company on dealer exchange, or simply returned as being unsatisfactory.

3. The guitar was completed in August or September of 1938 as part of a larger order, but then the order was reduced in size and the guitar was not immediately shipped.”