Zodiackillersite.com

<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.

Xcaliber wrote: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.

Xcaliber wrote: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:

1. The 'SAM SURVEY': "...instituted by the New York Office in December, 1959. It is a program by which airmail destined for certain European cities or countries is examined by Agents prior to its being placed in bags and placed aboard the planes. This examination is made for a twofold reason: (1) To identify persons corresponding with known Soviet mail drops in Europe (2) To identify and locate individuals in the United States sending letters to Europe which may be part of a Soviet illegal network."
2. The 'GUS SURVEY': a similar operation, this time "reviewing all of the mail received by a post office substation for distribution within its territory or zone."

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

FBI wrote: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.]

Xcaliber wrote: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.

Xcaliber wrote:<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.

Xcaliber wrote: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:

Sherlock Holmes wrote: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?