<That said, I don’t think we should be too worried. One of our three weekend letters – Belli – was hand-cancelled on a Saturday, whilst we have the example of the ‘Dripping Pen’ letter, which was alternatively machine-cancelled on a Saturday. So, even for Saturday, there are clearly both options available – the former, as we are supposing, being the method of processing hand-dropped mail to local destinations. It would at least seem likely, then, that the same would be the case for Sunday, but we’ll see, I’m sure.>

My thought is if it is established that the machine cancellers didn’t run on Sundays, we can then (hopefully) deduce that the two letters that received the Sunday hand post-marks did not receive them for the reason of being rejected by the machine cancellers.

My thought is if it is established that the machine cancellers didn’t run on Sundays, we can then (hopefully) deduce that the two letters that received the Sunday hand post-marks did not receive them for the reason of being rejected by the machine cancellers.

If that were the case though, X, wouldn’t we be at risk of losing more than we gain?

If all mail processed through Rincon on a Sunday were hand-cancelled, then this would include mail collected on a Sunday from mailboxes anywhere. Assuming there were such Sunday collections – maybe there weren’t.

I’ve had a look back at some of the examples of machine-cancelled postmarks that have appeared in this thread previously. Of the four in this post, the one for Houston, TX, which was machine-cancelled "PM 20 JUL 1969" – this was a Sunday.

That said, I’m always extra cautious about Houston, TX, postmarks from ’69. I haven’t retraced where this might have come from (source), but there’s always the possibility of the stamp being collectors’ (philately).

Generally, it’s difficult enough trying to search for any US postmarks from a specific year, so I’m not going to (at this point) try pinning a search down further to just Sunday postmarks.

To throw in one more twist, I read in a postal worker’s forum a couple of comments that indicated the automatic machines (nationwide) didn’t operate on Sundays. I may have picked this up out of context, and it may not apply to Rincon Annex in 1969.

X, are you able to recall where you saw this – which specific forum? I think it would be useful at this point to take a closer look at what, exactly, was being said.

Re: further confirmation of the central processing role of Rincon Annex, San Francisco.

In a collection of de-classified FBI documents from 1961, relating to two mail-focused operations involving counter espionage efforts, it is documented how these operated initially in NYC and how, after positive evaluation, they were expanded out to other cities, including San Francisco. The two linked operations were:

[list=1]

In relation to the GUS Survey operation in San Francisco in 1961, the focus on Rincon was apparently predicated on the following:

An estimated 130,000 pieces of first-class mail arrive in San Francisco daily from New York City and Washington, D.C. in sacks containing only mail originating in those cities and destined for delivery in San Francisco. It is estimated that about two-thirds of this total originates in New York. This first-class mail from New York actually arrives by air whilst that from Washington arrives by both air and rail. This mail arrives at Rincon Annex around the clock, and no firm figures are available at this time as to the volume arriving at any given time during a twenty-four period. [emphasis (italics) added.]

To throw in one more twist, I read in a postal worker’s forum a couple of comments that indicated the automatic machines (nationwide) didn’t operate on Sundays. I may have picked this up out of context, and it may not apply to Rincon Annex in 1969.

Okay, I found one.

The ‘Concerned Citizen’ mailing, in fact.

Postmarked 10 August 1969, PM – a Sunday – and clearly machine-cancelled. (By a Pitney-Bowes Mark II facer-canceller, no less!)

<Okay, I found one.

The ‘Concerned Citizen’ mailing, in fact.>

Excellent!

<Assuming there were such Sunday collections – maybe there weren’t.>

My instinct and memory are that there were a few mailboxes in San Francisco that had Sunday collections. Specifically the boxes in front of Rincon Annex, as well as the inside slots, if the lobby was open on Sundays.

<Assuming there were such Sunday collections – maybe there weren’t.>

My instinct and memory are that there were a few mailboxes in San Francisco that had Sunday collections. Specifically the boxes in front of Rincon Annex, as well as the inside slots, if the lobby was open on Sundays.

I saw something similar stated in an old, 2007, thread on ZK.com, talking about the Stine letter and whether it had blood stains on it from the enclosed shirt swatch (which it doesn’t) and when/where it might have been mailed.

Anyway.

We’ve now got three letters that were postmarked on a Sunday. Collections will have been minimal on a Sunday in any event, and likely just from mailboxes in and around Rincon. One letter – ‘Concerned Citizen’ – was machine-cancelled. The Zodiac ‘Bus Bomb’ and ‘Little List’ letters were hand-cancelled. The hypothesis is that the hand-cancellation signifies local destination (local to Rincon). Both the Zodiac letters were local to Rincon – just a few blocks away at the offices of the Chronicle. The ‘Concerned Citizen’ mailing was going to Vallejo.

Q: Are we happy yet?

(X, I’m gonna be honest. I learnt my lesson a while ago. If there’s a hole in an argument, you’ll find it. So, I’m not going to allow myself to be happy until at least you are!)

<The hypothesis is that the hand-cancellation signifies local destination (local to Rincon). Both the Zodiac letters were local to Rincon – just a few blocks away at the offices of the Chronicle. The ‘Concerned Citizen’ mailing was going to Vallejo.>

I have to admit, it does seem unlikely that they would take the time to hand-separate mail that was destined for nearby addresses. It’s possible that, for whatever reason, they hand-posted all mail that was deposited in the ‘Local’ freestanding boxes in front of Rincon. I guess that would mean, in the case of the Citizen letter, that it was deposited in a freestanding ‘Out of Town’ box in front of Rincon, and that the ‘Out of Town’ mail fed into the bulk machine cancellation processing.

It would admittedly be hard to understand the logic for this.

The other possibility for the Citizen letter is that it was collected from a freestanding city box (not Rincon) late on Saturday and didn’t receive the postmark until Sunday pm.

I thought of one more thing — that I believe major post offices like Rincon may have had a dedicated freestanding box and/or lobby slot for specifically mail within the zip code. Unfortunately I see the Rincon Zip was 94105 and the Chronicle was 94103.

I have to admit, it does seem unlikely that they would take the time to hand-separate mail that was destined for nearby addresses. It’s possible that, for whatever reason, they hand-posted all mail that was deposited in the ‘Local’ freestanding boxes in front of Rincon. I guess that would mean, in the case of the Citizen letter, that it was deposited in a freestanding ‘Out of Town’ box in front of Rincon, and that the ‘Out of Town’ mail fed into the bulk machine cancellation processing.

It would admittedly be hard to understand the logic for this.

Was it the case that there were separate freestanding mailboxes for ‘Local’ and for ‘Out of Town’ mail? This feels important.

As to assessing the logic, I suppose I’m quite led by the old adage:

Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.

What other possible explanation do we have left for the existence of the three weekend-only, hand-cancelled letters?

<Was it the case that there were separate freestanding mailboxes for ‘Local’ and for ‘Out of Town’ mail? This feels important.>

I’m quite sure there were. Even the other day in my small local post office I noticed dedicated deposit slots in the lobby for ‘Local’ and ‘Out of Town’. Major post offices typically additionally had dedicated similarly-marked freestanding boxes in front. ‘Local’ meant San Francisco specifically as opposed to the greater Bay Area, so Vallejo would have been ‘Out of Town’.

<What other possible explanation do we have left for the existence of the three weekend-only, hand-cancelled letters?>

If I’m still thinking clearly (!), the original and most uninteresting one — that they failed the machine cancellation process due to bulk or shape?

One more question:

What would be the reason for the automatic machines to be operating on Sundays, if there were few Sunday mailbox pickups in San Francisco and the two counties?

Were the machines simply handling the overflow from the Saturday pickups?

<Was it the case that there were separate freestanding mailboxes for ‘Local’ and for ‘Out of Town’ mail? This feels important.>

I’m quite sure there were. Even the other day in my small local post office I noticed dedicated deposit slots in the lobby for ‘Local’ and ‘Out of Town’. Major post offices typically additionally had dedicated similarly-marked freestanding boxes in front. ‘Local’ meant San Francisco specifically as opposed to the greater Bay Area, so Vallejo would have been ‘Out of Town’.

So, if this can be confirmed, I think it would support the basic premise that there could have been different processing of the local from the out-of-town mail between the ‘Bus Bomb’ and ‘Little List’ letters and ‘Concerned Citizen’ to perhaps explain the former having been hand-, the latter machine-cancelled.

<What other possible explanation do we have left for the existence of the three weekend-only, hand-cancelled letters?>

If I’m still thinking clearly (!), the original and most uninteresting one — that they failed the machine cancellation process due to bulk or shape?

I suppose this, more than anything, is something we will never have absolute confirmation of. From a probability standpoint, however, I currently am happy to go with the great unlikelihood that 3/4 letters would have had to have failed the process at weekends, none on weekdays. The Belli letter certainly (one page plus shirt strip) was no different, in this respect, from the Stine letter.

One more question:

What would be the reason for the automatic machines to be operating on Sundays, if there were few Sunday mailbox pickups in San Francisco and the two counties?

Were the machines simply handling the overflow from the Saturday pickups?

Overflow handling is a possibility, and if we do get the help of an SF postal worker from the time it will be important to put this as a question. We haven’t really looked at this angle yet, although it has been considered elsewhere and in other threads here, I think.

The issue I would have with this, without confirmation to the contrary, is the one which would arise from the ‘legality’ of postmark dating. From what I have understood from having read through the postal procedures from various periods, it is strongly acknowledged that postmark dates have a legal importance in terms of proof of when mail was mailed. The official ‘definition’, if you like, of when a letter is so mailed seems to have consistently been that of when it arrived into the possession of the Postal Service at the SCF. Intentionally mis-representing a postmark date appears, in consequence, to have been a serious offence for postal workers.

So, I’d have to wonder what constitutes ‘possession by the SCF’.

Would sitting in a bag at the facility awaiting overflow processing from the previous day constitute ‘possession’? We’d need this, like several other things, directly confirming. However, I wonder about the possibility that mail having arrived at the SCF in an AM/PM slot for a particular day, but not actually run through the cancellers owing to some backlog or overflow before the end of that slot, would have its arrival time honoured nonetheless? So, could it be the case that Saturday overflow, in this sense, if having arrived at the SCF on the Saturday, even if late, would yet be required to be postmarked Saturday PM? Or do they just hit a halt at 12:00 noon and 17:00 hrs and call “change the dater” regardless? I don’t know.

The other issue I would have is, what would cause the necessity of an overflow of this kind from a Saturday which, excepting the Sunday itself, must surely be the lowest bulk-mailing day of the week?

If, however, the overflow was processing mail that had been posted in mailboxes very late on the Saturday, so as not to make a Saturday collection, then we’d again need direct confirmation of some sort as to Sunday collections – even though minimal – avoiding the AM, to get only PM postmarks.

Just chiming in to say that the person who wrote the article linked below might be able to answer some of your questions. Although it looks like he didn’t work at Rincon, he had a 40-year career with the USPS in San Francisco starting in 1966 and seems to be interested in postal history.

http://www.sfcityguides.org/public_guid … 2=&topic=B

An email address (from 2006…) can be found here:

http://answers.google.com/answers/threa … 08705.html