Of course, the motto you refer to is not officially connected with the US Post Office, even though it is mistakenly thought to be by many:
http://about.usps.com/who-we-are/po...on-motto.pdfIn any event, it is certainly an interesting postal marking for the day. In fact, fast forward to the present day and it still is a problem in some areas of the country as this news article will attest to:
http://www.washingtonpost.com/polit...8_story.htmlCuriously, the 1909 postal marking shown is probably somewhat scarce, as it is not even carried on the Auxiliary Markings website (at least not that I can see). Actually they may be interested in a copy of your cover to document the use of that postal marking:
http://www.postal-markings.org/listing-full.htmlIt's also curious to think that the situation "Delayed by expiration of carrier's time" occurred often enough that the post office felt it necessary to create a rubber stamp specifically identifying that as a cause for the mail delay.