The first letter to return was addressed to Bermuda! It arrived on 30 August 2019, two days after the initial dispatch. However, this return was due to USPS’ scanning machine mistaking the return address for the destination address. This happens from time to time with my mail.
I deposited the letter at my local post office mail drop per Post Office rules on how to handle misdelivered mail on Tuesday, 2 September. I have not seen it since.