Regardless, I don’t see how any of this information is relevant to the original aim of this thread which was to try and pin point where Zodiac mailed his letters from.

We were for a while running with the idea that possibly the three hand-cancelled letters might have been dropped at sub-post offices near to their destinations and thereby processed in a manner diverting them from the Sectional Center Facility, which would have given us some clues as to which post-offices these may have been dropped at. Unfortunately, however, everything to date appears to be pointing away from such a possibility.

Regardless, I don’t see how any of this information is relevant to the original aim of this thread which was to try and pin point where Zodiac mailed his letters from.

We were for a while running with the idea that possibly the three hand-cancelled letters might have been dropped at sub-post offices near to their destinations and thereby processed in a manner diverting them from the Sectional Center Facility, which would have given us some clues as to which post-offices these may have been dropped at. Unfortunately, however, everything to date appears to be pointing away from such a possibility.

Agreed Shaq, and expertly-stated all around.

I guess one thing to try to confirm is did the sectional center alternately hand-post mail, and if so for what reasons.

Would a letter containing a shirt piece typically not be machine-postable, and would an envelope containing five pages be similarly non-machine-postable.

Also to confirm — was Rincon Annex the sectional center back then — and was a letter mailed in the drop-slot inside Rincon Annex handled the same way as incoming bulk mail to the facility.

I guess one thing to try to confirm is did the sectional center alternately hand-post mail, and if so for what reasons.

Would a letter containing a shirt piece typically not be machine-postable, and would an envelope containing five pages be similarly non-machine-postable.

Also to confirm — was Rincon Annex the sectional center back then — and was a letter mailed in the drop-slot inside Rincon Annex handled the same way as incoming bulk mail to the facility.

On the question of whether Rincon Annex was the SCF, the closest that I have come to providing evidence for this is the following:

In a 2018 blog article by an author who lived through the March 1970 Postal Strike, he writes:

Rincon Annex, where I worked, featured beautiful WPA-type murals in the lobby, which have thankfully been saved as iconic examples of social-realism—but in the 1960s and 1970s there was nothing artistic about the working areas, which featured surrealistic fluorescent lights and the constant roar of mail-sorting machines.

His "surrealistic fluorescent lights and the constant roar of mail-sorting machines" certainly suggests SCF to me.

I don’t know what others think?

Also to confirm — was Rincon Annex the sectional center back then — and was a letter mailed in the drop-slot inside Rincon Annex handled the same way as incoming bulk mail to the facility.

X, every time I’ve come back to this thread of late feeling a little deflated that we’ve probably exhausted all hope of leads, I discover that either you or Simplicity have managed to come up with some new angle that brings it all alive again.

So. Not wanting to make any prejudgement about what the answer is to your quoted question (above), let’s just have a look at one possible scenario if this were true, and applied in the instance of the hand-cancelled letters.

We’ve already ascertained that the function of the SCF in San Francisco was to process mail not just from the city, but also from places like San Mateo, Santa Clara, Mare Island (Navy). The possibility remains, then, that the majority (if not all) of the mailings could have come from anywhere in this broad area. So. If this were the case, what might have led Zodiac to want to come in to San Francisco to post the three letters that show they have been processed differently, in some way, being hand-cancelled?

Well, firstly – to take the first two of the three letters – these are distinctive, compared to all the other letters, for the one reason that they both contained sections of Paul Stine’s shirt.

Now, as to all the other letters – including those with ciphers – if there was any problem with the mail and they didn’t get to their intended destinations, then they could simply be written out again and resent. Not so, however, with sections of Stine’s shirt. These are irreplaceable. Zodiac is likely going to want to take extra steps to ensure that the chances of these getting lost are minimised, as far as possible.

How, then, might this be achieved?

Bring them to the SCF directly and drop them in the outside mailbox, and surely outside of counter hours to minimise risk of discovery.

Then, perhaps in support of this, think about what we know from the dates on which the attacks occurred. These are all strongly suggestive of the fact of the killer having significant commitments during the regular week, and being available to kill on weekends and public holidays.

All three of the hand-cancelled letters were post-stamped either Saturday or Sunday, fitting this profile.

Were we, then, to get a helpful answer to your question, X, and were this to indicate strongly that these letters were hand posted at the weekend at what is very likely (it seems to me) the SCF at Rincon Annex, then the following hypotheses might gain some interesting weight:

• that greater probability would attach to the idea of Zodiac not living in San Francisco, but in one of the more remoter regions, as this would be consistent with greater (perceived) risk of mail being lost;[/*:m:34790vbz]
• that, in order to bring these letters into San Francisco for mailing, he could only do so at weekends outside of his regular week-life patterns; and[/*:m:34790vbz]
• that, in doing so – owing to the location of the Rincon Annex to the far East Side of San Francisco, close to the Bay Bridge – it would be strongly suggested that this might have been his route in, thus indicating that he was coming from Mare Island, via Vallejo (he wouldn’t have needed the bridge from San Mateo, Palo Alto, etc.)[/*:m:34790vbz][/list:u:34790vbz]

[Edit: spelling]

“This isn’t right! It’s not even wrong!”—Wolfgang Pauli (1900–1958)

 

This is very good, there’s much to process here.

Separately for a moment, the Stine letter apparently passed through the automated cancelling system at the sectional center, and of course it too contained a piece of the shirt.

Separately for a moment, the Stine letter apparently passed through the automated cancelling system at the sectional center, and of course it too contained a piece of the shirt.

This is so. That said, I don’t think it would be difficult to plausibly argue that Zodiac had his hand forced a little here.

The murder of Stine took place on the evening of 11 October, a Saturday. According to your excellent analysis, which I can accept, he likely made a quick escape over the Golden Gate bridge as most convenient. The next day, the Sunday, he would have been looking for news and concerned, in the first instance, about whether and how much he had been seen, and would surely have uncertain worries as to whether he was recognisable. I would suggest that this would make San Fran too hot for him to return to on the day after the murder.

That said, he wouldn’t want to wait to the following weekend either to head over to Rincon (if this is what he would have preferred) and get the shirt piece and letter to the Chronicle, so it pretty much had to go into the regular mail, to be processed in the regular way.

And it looks like this is what happened, the letter going through the facer-canceller and receiving a postmark of Monday PM (13 October, two days after the shooting).

I don’t understand this fascination with Rincon. He could have dropped it in any mailbox in the SF area or taken it to any post office. I don’t believe he would know the ins and outs of the postal service. I mean I don’t even know where MY SPC is. Do you know what your SPC is? How would Z?

I don’t understand this fascination with Rincon. He could have dropped it in any mailbox in the SF area or taken it to any post office. I don’t believe he would know the ins and outs of the postal service. I mean I don’t even know where MY SPC is. Do you know what your SPC is? How would Z?

Again, to summarise.

We have discovered from various sources that all mail across at least four major 3-digit Zip-code regions (940, 941, 943 & 944) were, at the time in question, undoubtedly routinely processed at the SCF for San Francisco. We also know that, barring any exceptional circumstances that we are just now beginning to look at, mail arriving in this way would have been routinely machine-cancelled through the then-in-operation Pitney-Bowes Mk II face cancellers.

Three of the Zodiac letters were not so cancelled, hence we have three exceptions. Why?

The first two of these letters were both cancelled Sunday PM, so whatever the ‘exceptional circumstance’ was in each of these cases, it cannot have involved any form of alternative hand-cancelling at a local post-office. These two, although hand-cancelled, must still have been processed at the SCF.

It has yet to be confirmed (or otherwise), but there is much to point to the SCF for San Francisco having been at Rincon Annex. Note, however, if confirmed as such, it was not just such. It was also a functioning counter post office and, for people aware of it as such, they would have been aware (if true) of it’s SCF status also.

So, were we to ascertain – as we are currently researching – that the ‘exceptional circumstances’ that relate to the three hand-cancelled letters are that these letters were hand-delivered to a mailbox at Rincon Annex outside of counter hours (Sat/Sun), then we would have identified this location as where Zodiac had mailed three of his letters (two with pieces of Stine’s shirt); which may or may not, in turn, suggest that the others that went through the regular processing were mailed from outside San Francisco.

I would therefore argue that the current focus on Rincon Annex/SCF is very much in line with the question posed in the OP:

Do we know where each letter/card/cipher was mailed from? I know they were mailed from the city, but I mean do we know the specific mailbox locations each correspondence was sent?

Shaq, it’s an important focal point.

I could be wrong but I’m remembering Rincon was the go-to post office in San Francisco when you needed a timely postmark. I believe the lobby was open quite late and that it was understood that if you mailed your letter inside the lobby before the pickup deadline, that your letter would receive that day’s postmark.

The timely postmark likely wouldn’t apply to the Zodiac in terms of any strategy, but again it might mean that the letters dropped directly at Rincon were processed differently than the imported bulk, and therefore for whatever reason those 3 received the hand postmarks.

Your thought is an excellent one, that he likely wanted to minimize the excess handling of the letters containing shirt pieces, and therefore would have mailed them where he assumed he’d best cut out the middleman.

The first two of these letters were both cancelled Sunday PM, so whatever the ‘exceptional circumstance’ was in each of these cases, it cannot have involved any form of alternative hand-cancelling at a local post-office.

Why?

Okay. Earlier today I posted a link to an article about the US postal strike of March 1970. As noted, the author of the article was someone who was working at Rincon Annex at the time. The article itself doesn’t give any contact details for the author, but a brief search has brought up that he is, among other things, a published author of novels. I’m thinking it would be good to get in touch with him to help us clear up a few things. I’m hoping I can find a publicly available contact e-mail for him.

So, without wishing to bombard him with a million-and-one things at once, what might be the key questions we would want to ask at this point?

The first two of these letters were both cancelled Sunday PM, so whatever the ‘exceptional circumstance’ was in each of these cases, it cannot have involved any form of alternative hand-cancelling at a local post-office.

Why?

Because, as far as everything I’ve seen, US counter post-offices were not open on Sundays since 1913.

Okay. Earlier today I posted a link to an article about the US postal strike of March 1970. As noted, the author of the article was someone who was working at Rincon Annex at the time. The article itself doesn’t give any contact details for the author, but a brief search has brought up that he is, among other things, a published author of novels. I’m thinking it would be good to get in touch with him to help us clear up a few things. I’m hoping I can find a publicly available contact e-mail for him.

So, without wishing to bombard him with a million-and-one things at once, what might be the key questions we would want to ask at this point?

I already emailed this gentleman, and I have not yet received a response.

Your thought is an excellent one, that he likely wanted to minimize the excess handling of the letters containing shirt pieces, and therefore would have mailed them where he assumed he’d best cut out the middleman.

And, I hadn’t noticed this before but, if you take a look at the envelope for the Stine letter (which contained the first piece of shirt):

Zodiac has included his cross-hair symbol actually on the envelope.

Is this the only time he did this (for an enveloped letter, that is; he did, if we accept their authenticity, include the symbol on the two postcards)?

Perhaps being, as I have suggested, likely forced into having to remotely mail this letter so as to avoid any delay, the inclusion of this symbol might have been his insurance policy. Had his intention been the hope that this would get noticed early in the mailing chain, so that the letter would get pulled and forwarded to the police directly with, again, minimum delay and minimum risk?

I’m not sure I’m buying that. I have the polk directories for 1968 through 1972 in front of me. The Rincon Annex is listed under "branches" for the post office. Not a negative as, if I am remembering correctly, a sectional can also take in mail from the public like any other post office. However, I am looking for "sectional center" in all but not finding it. I do see "regional office" in all. The regional office is located at 631 Howard Street. Is this the sectional center given your contact states "regional"? Maybe.

I’m not sure that I can think of how to make any further progress towards pinning down the specific location for the San Francisco Sectional Centre Facility in the late 60s/early 70s. I can pretty much duplicate from another source what you, Soze, have found from the Polk directories (and will summarise this below), but I cannot find anything that straight-up says "this is where the SCF is." Short of either 1.) having someone tell us, or 2.) going through the whole Polk directory street-ordered listings until we stumble across it (because it must have some address), I don’t know where to go from here.

Anyhow. I’ve been looking closely at the United States Post Office Department (pre-USPS, remember) Directory of post offices, with ZIP codes. 1969.

On p. 7 it describes how the national postal service is "divided into fifteen regions," (not sections), San Francisco being one of these.

For the SF regional office, it gives the Howard street address that you had found from Polk. It then lists the ‘Sectional Centres’ (on broad Zip code only – come ON!), providing pretty much the same information that we had from our historian source and little more.

Under ‘Sectional Centres’, it says:

Listed below are the sectional centers in alphabetical sequence by State showing the first three numbers of all ZIP Codes to be routed through these sectional centers.

The three-digit codes shown in italics are those of multicoded cities having their own three-digit identification and are not considered sectional centers.

(But am I reading this correctly? It looks like it’s saying the Sectional Center Facility for San Francisco is under a 940 postcode?)

Finally, there is the actual list of post offices:

As you can see, everything listed is either a ‘Branch’ (B) or ‘Station’ (S), except for "San Francisco, 1" which I would suggest is the main office at the Howard Street address.

So, even the contemporary USPSD Directory of Post Offices is not interested in documenting for the public the location of its Sectional Center Facility.

Browsing old posts and came across this post again. I think you are right. I believe that’s exactly what it’s saying: the sectional is under 940 zip. South San Francisco rather than simply San Francisco. Interesting.

Soze