What Was The Purpose Of Including A Timestamp In Older Postmarks?

I did a quick search and couldn't find an answer to this question which I've been wondering about.

Was there a practical reason why older postmarks included timestamps in addition to the date? I've seen U.S. covers with postmarks showing an a.m. or p.m. designation and some older Canadian postmarks with a timestamp in the postmark down to the half hour.

Just wondering how important this information was and how it was used back in the day? Or was it just a nice detail?

When delivery local was done within hours and not much slower beyond local, it was good information. This alerted postal employee how long the mail had been sitting around since receipt for delivery.

By USPOD rule, third class and the new (1-1-1913) parcel post system was not to use time nor dates in the cancels, Month was fine.

Today mail service is much slower. The last six out eight items I have mailed first class with stamps have taken an average of over 2 WEEKS from the west coast to Chicago and farther east.

Time sensetive mail like special delivery received documentation of speedy delivery.

Times were also used to indicate which batch of mail the letter was in since there were often multiple dispatches of mail out from a given post office throughout the day.

In the 19th century the time could assist with identifying late fee and too late mail.

Time was very important to the USPOD, particularly after the civil war and into the mid 20th century when so much mail was carried by train (and later by plane) on exacting schedules, large cities had multiple deliveries, etc. Being able to track the mail was important (especially delays and errors) in the era of increasing mail volumes, increased mechanization, and time/motion studies. Efficiency was very important.

Several inventors developed canceling machines with clock mechanisms to cancel mail "to the minute". The experimental Mallonee and Malmborg machines of the 1890s were followed in the early 20th century by machines of the Time Marking Machine Co which saw significant use in larger offices, although few machines kept their clocks in working order. Here are examples from Madison, Wisconsin with a working clock:



This feature was probably more of a marketing gimmick to get their machines adopted by the USPOD rather than a necessity as it was not adopted by other competing machine manufacturers of the era.

In general, the instructions in the "Postal Laws and Regulations" volumes have instructed postmasters over the years to change the time element of their cancels as frequently as their devices had time slugs provided. In most medium-sized and larger offices this was typically every half hour and occasionally every quarter hour. Many of the 3rd and 4th class offices often had only an "AM" and "PM" options for their 4-bar handstamps used in the early 20th century.

Interestingly, many of the sprays of the 1990s contained the time down to the minute:

Thanks John and others. It hadn't occurred to me that they might be doing their own efficiency tracking using these time stamps. I appreciate seeing all the examples and good information.

The point about their time consciousness in moving the mail is also a good one. We don't think about that today. You drop your mail in the box and figure it will get to its destination sometime.

Indeed. Before WWI, London had ten or twelve deliveries a day - you could let your family know you'd be home late for tea.

I will add another example from a few decades ago. In the facer-canceller era of the last third of the 20th century, there are three typical time slugs, AM, PM and -PM. The AM slug is rather uncommon as most mail is processed in the afternoon/evening.

I understand the "minus PM" or "dash PM" time slug means the letter was received/processed after the day's cut off for making transportation connections, etc., and would count as the next day's mail for calculating delivery time efficiency. The extra day being customer's fault rather than the USPS.



And I've always liked this one with "NOON".

Wasn't "12 M" also used for "NOON?" How would this relate tracking efficiency? Does it actually mean that mail was despatched at 12 Noon, or at least during the Noon hour? My understanding ot the use of AM/PM in 3rd and 4th class offices simply indicated whether the mail was dispatched before or after noon. What would 12 M or NOON signify?

"Noon" is just another time slug, although uncommon.

I would hesitate to use the word "dispatched", which to me implies "sent onward" from the origin post office. Mail was faced and cancelled fairly quickly upon receipt at the origin post office as the first step in considerable sorting, bundling, sacking/traying process. The mail might then wait for the scheduled transportation.

Bottom line, I suspect the USPOD/USPS looked at very little mail in this detail, but when they wanted time/efficiency data, they could easily get it.

Go figure. And I always thought "12 M" meant "12 Midnight", for all those people who needed to get their items postmarked by midnight a certain day. But you are correct, I looked it up and "12 M" is the standard abbreviation for "12 Noon" (the M standing for Meridiem, just like AM is ante meridiem (before mid-day) and PM is post meridiem (after mid-day), so "12 M" simply means exactly noon mid-day.

I also learned a new (old fashioned) word the other day. A message on a 1920s postcard said "I will arrive Saturday forenoon." This wasn't just messy handwriting, the dictionary says that forenoon is a word that means "before noon" (the opposite of afternoon), or what we today would call morning. Seems logical. I wonder what caused the word to fall out of favor.

Also, meridian is neither AM or PM as it is the point between the two; thus, there is no such time as 12 AM or 12 PM. I believe there is a now obscure court case arising with the USPOD (NOT USPS) a long time ago, late 19th or early 20th century.

One reason for the date is to document when the mail was collected. For example if you mailed your taxes and such was due by April 15th, the correct day of mailing was important.

There are other collection time and dating nuances but those are too detailed for here.

Now I dislike participating in such discussions as this because "common sense" of the mob masses is WRONG, just like asking what years are in a decade (2011-2020) or what years are in a century (1901-2000) or what years are in a millennia (1-1000, 1001-2000, 2001-3000); the politics of BC and AD and the other political challenges to time and calendar keeping.

.... and one reason I chose not to address 12pm or 12am. :)

Well, I've known that 12 M was "noon" for some time, but I thought it stood for "midday!" But "meridian" makes sense, as AM is "antemeridian" and PM is "postmeridan." So of course, there can be no "12am" or "12pm."

Prior to WWII it was very common that large European cities had mail carriers delivering mail up to seven times a day, which also made it necessary to empty street mailboxes several times a day. Prior to WWI it was even more.

The time slot of a postmark indicated at what time mail had been received by the postal service at the collecting post office. It was also common in many European countries (the more of them the further back in time we go) to place an arrival postmark to the backside of the cover by the postal service at the delivery post office.

The only sort of letters where this procedure has survived are special delivery letters that are sent without a barcode sticker.