When the person said regional I am assuming he is talking about the sectional center?

Yes, ‘Sectional Center Facility’ (SCF), which – it has been suggested to me – was run from the Rincon Annexe Post Office, 101-199 Mission.

When the person said regional I am assuming he is talking about the sectional center?

Yes, ‘Sectional Center Facility’ (SCF), which – it has been suggested to me – was run from the Rincon Annexe Post Office, 101-199 Mission.

I have the location as 1300 Evans Ave. This came from USPS. I understand locations can change. Where does mission originate from?

Soze

Would machine errors matter, if the letters were all processed at the main hub?

Still – wondering if there were other clues as to mailing locations, that LE picked up.

No to first paragraph.

I’ve caught the mailing early. Not sure what it means though if anything. Cradle posted a USPS document some pages back that was yellow in color. Bottom right it talked about mailing early for speedy delivery. He used an Eisenhower stamp (I believe) that included this same thing. Again, not sure what it means. Z clearly thought it did.

Soze

Yes, ‘Sectional Center Facility’ (SCF), which – it has been suggested to me – was run from the Rincon Annexe Post Office, 101-199 Mission.

I have the location as 1300 Evans Ave. This came from USPS. I understand locations can change. Where does mission originate from?

The suggestion was added to the reply that I got from the historian at the Post Mark Collectors Club. Specifically, this was the reference:

Mail is gathered from all over that area (and these days from Marin and beyond, as well) and brought to the plant for cancelling and sorting, all in one operation. Now that plant is in an industrial area off of I-280, but in 1969 it may have been at the old Rincon Annex, I’m not actually sure.

The "industrial area off of I-280" is clearly the current 1300 Evans location.

Rincon Annex is on the National Register of Historic Places in San Francisco (#79000537) as retired by the USPS in 1985.

Apparently, there was a national stoppage of postal employees during March 1970 which was considered of such national significance that military had to be called in to "assist the USPS in maintaining essential postal services." I just happened, in my searching, to stumble across an absolutely fascinating Department of the Army declassified document dated 27 August 1970, with the subject After Action Report, Operation GRAPHIC HAND.

On p. 209, in relation to the ‘field activity ‘documented for the afternoon of Sunday, March 22, 1970, it reports:

San Francisco and Los Angeles are partially out. Many pickets, especially at Rincon Annex, are not identifiable as postal workers. 12 smaller California offices voted to strike Monday if San Francisco stays out.

Whilst I have to acknowledge that this doesn’t specifically reference Rincon Annex as having been the SCF for San Francisco in 1970, it would seem likely that the focus of picketing would be on the major centers.

I’ll see what else I can find out.

<Still don’t think we will ever pin a location. We aren’t privy to that knowledge about machine error locations.>

Would machine errors matter, if the letters were all processed at the main hub?

Still – wondering if there were other clues as to mailing locations, that LE picked up.

I stumbled across a paper from 1977, entitled ‘Manpower Allocation in U.S. Postal Facilities: A Heuristic Approach’,* which is basically a research paper looking at "how to generate efficient employee work schedules for the work force in a large mail sorting facility of the U.S. Postal Service."

It is (for me, at least) a very technical paper. However, it does start off with some basic information about "Mail processing and dispatch schedules" in place at the time:

A typical SCF has 20 identifiable work centers for processing the different mail categories. Each of these work centers represents a different kind of processing operation. Mail arriving at an SCF for processing may pass through several of these work centers before it is ready to be dispatched. The routing of mail through the work centres is a function of the mail’s priority designation, physical characteristics, and destination.

It goes on to give a schematic for such a system of ‘work centers’.

So, given this basic description, I’m wondering whether it was possible at the time for LE and/or FBI to liaise with SCF to back-trace the letters, based on the machine/die codes, through the specific work center routes then in operation, in order to be able to work out by what route (source) the letter arrived at the SCF?

I don’t know how detailed this hypothetical back-tracing might have been. I’m pretty sure, however, that 50 yrs on we would not be able to reconstruct it.

(BTW. I may have missed something, but what are "machine error locations?" Thanks.)

[*Ref: Showalter, M. J., Krajewski, L. J. & Ritzman, L. P. (1977). ‘Manpower Allocation in U.S. Postal Facilities: A Heuristic Approach’. Comput. & Ops. Res., Vol. 4. pp. 257-269.]

(BTW. I may have missed something, but what are "machine error locations?" Thanks.)

The machines generating the error codes 1a, 1b, etc and the machines physical location.

Soze

<So, given this basic description, I’m wondering whether it was possible at the time for LE and/or FBI to liaise with SCF to back-trace the letters, based on the machine/die codes, through the specific work center routes then in operation, in order to be able to work out by what route (source) the letter arrived at the SCF?>

Very interesting angle!

Here is part of what I wrote in 2011 regarding the mail processing:

Mail carriers will pick up all mail from collection boxes several times a day within their area of work. They take this newly collected mail to the postal facility they work out of where it is bagged for distribution to the central mailing facility.

After it is bagged, it is placed on a truck for delivery to the central mailing facility. There are 264 central mailing facilities, some of which serve hundreds of post offices and that they process nearly all the mail coming from or going to their regions.

Once at the central mailing facility, the mail is sorted according to envelope size by feeding it through a machine called an edger-feeder. This machine feeds the mail into another machine called a facer-canceler. The facer-canceler has sensing devices that determines where on the envelope the stamp is located and then the machine arranges the envelopes so that the stamps all face in the same direction. The facer-canceler then places black lines over the stamps so that the stamps cannot be used again. After the lines are placed on the stamp, the machine then postmarks the envelope.

The postmark includes the date, the name of the sectional center, an abbreviation for the state, a three- or five-number zip code and, the time period during which the letter was received at the post office (I believe in this case it was the sectional center). Letters received between midnight and noon are postmarked A.M., and those received between noon and 5 P.M. are marked P.M. Letters that arrive at the post office (sectional center) between 5 P.M. and midnight are postmarked – P.M. That, I had long forgotten seen.

Mail addressed to locations outside the region served by the sectional center, is transported by truck, plane, or train to other sectional centers for sorting. Nearly all first-class mail going more than 200 miles travels by plane (airmail)

Taking into consideration what I read and viewing the postmarks on the envelopes the Zodiac mailed, I called my local Post Office and asked them a few questions. The first question that I asked concerned the postmark and lines shown on the envelopes. I wondered if it was possible to hand stamp an envelope at the postal facility it was mailed then have it sent from, that postal facility to the sectional office, for further stamping of the line on the stamps themselves. The answer was no.

If an envelope is received at a post office, it is bagged and sent by truck to the sectional office. At the sectional office is where the postmark occurs. Now, I asked how one would tell what particular branch an envelope would be mailed from originally and was told by the city on the postmark. This left me a little confused but before I could ask or further drill my point, she stated the following:

I live approximately 50 miles from the city of XXXX, which houses the main postal branch (or sectional office) for this area. If I had lived in the next town over (another ten miles or so), my mail would actually have a XXXX postmark (which, by the way, is roughly 2 hours from where I live) I guess the point I am trying to make here with this information is that in order to know when the letter was postmarked or received, you would need to know the location of the main branch and what cities the main branch covers. Since I live approximately 50 miles from the main branch and, I know for fact the sectional truck is at my local post office at approximately 4 P.M. daily, then I could say with almost certainty that my mail will be delivered to the main branch after hours and post marked – P.M. because XXXX is roughly an hour from where I live. The fact that the postmark shows a P.M. doesn’t necessarily mean that it was received at the post office in the P.M. but means it was a time frame in which it was received at the sectional center. It could have been mailed at a post office in the A.M. and arrived at the sectional office in the P.M. for processing. This is where you would need to know all of the postal offices within a postal section.

I was later asked "Since Zodiac did not put a zip code on his letters until after he was required to do so I wonder if it made a difference on how the letters were handled. It looks like the sectional centers were all about mechanizing the process but if there was no zip for a machine to read, how was that processed?"

This was the answer: A computerized machine called a zip mail translator sorts the postmarked letters according to their destination post office. Postal workers push buttons on the machine’s keyboard to send each letter on a conveyor belt into one of hundreds of bins. Each bin holds mail for a different post office.

I think we can do roughly the same thing we were attempting to do with the mailboxes but this time with the sectional centers. We would have to map a wider area though. Time and travel distances would be key too.

Soze

I live approximately 50 miles from the city of XXXX, which houses the main postal branch (or sectional office) for this area. If I had lived in the next town over (another ten miles or so), my mail would actually have a XXXX postmark (which, by the way, is roughly 2 hours from where I live).

I think we can do roughly the same thing we were attempting to do with the mailboxes but this time with the sectional centers. We would have to map a wider area though. Time and travel distances would be key too.

The first paragraph I believe is significant and the reason I make the second.

Soze

I don’t know why it is so hard for Google to answer a simple question like "When did the San Fran. USPS move to 1300 Evans?"

So, I’ve had to resort to some deeper research.

The closest maps of San Francisco that I can find to the 1969/70 period are from 1966, in the David Rumsey Historical Map Collection. It is very clear on the 1966 map I have looked at that, whilst the Rincon Annexe post office is clearly shown:

nothing is likewise shown for the Evans location of the current USPS Sectional Centre Facility:

More to the point, it is evident from overlaying this second map on a modern (2019) Google map of the same region that there has clearly been some significant land reclamation in the area of India Basin since 1966.

The red box in this image marks the location of the current SCF at 1300 Evans which, as can be seen, would have been largely under water as late as 1966.

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. But then in 1969 and 1970 a new listing for the PO pops up. It’s called the "Postal Concentration Center (Time Section). I am curious what is meant by "Time Section". Anyhow, that address is 390 Main Street (corner of main and Harrison. Large building. Covers whole block.) It’s at this location from 1969 through 1972.

Page numbers for post office in polk directories are 832, 844, 842 and 696 for the years 68, 69/70, 71 and 72 in that order.

Anyway, I’m thinking we might need the postal concentration center at 390 main and not Evans or mission.

Soze

Just to clarify my previous post, which was in context perhaps likely to mislead. In illustrating that Rincon Annexe was shown on the 1966 map I was merely wanting to confirm that this particular map was showing post offices. Some maps I have found from around the period don’t. I wasn’t wanting to suggest that this means that Rincon served the function of the Sectional Centre before USPS at Evans.

Just to clarify my previous post, which was in context perhaps likely to mislead. In illustrating that Rincon Annexe was shown on the 1966 map I was merely wanting to confirm that this particular map was showing post offices. Some maps I have found from around the period don’t. I wasn’t wanting to suggest that this means that Rincon served the function of the Sectional Centre before USPS at Evans.

That’s how I took your post. It’s all good though.

Soze

Anyway, I’m thinking we might need the postal concentration center at 390 main and not Evans or mission.

This reference "postal concentration center" certainly sounds promising. However, through my searching (again, difficult – has Google got worse somehow, or what?) every reference I have been able to locate specifically has some connection to agreements between the USPS and the armed forces for military mail processing.

For example, in a 2000 USPS handbook, Post Offices Serving Department of Defense Installations, you have:

Appendix A: Publication 38
Postal Agreement With the Department of Defense (February 1980)
…
IV. Responsibilities
…
B. The United States Postal Service agrees to:
…
2. Establish and operate postal concentration centers, as needed, for the concentration, sorting and delivery or dispatch of military mail in accordance with requirements for the Department of Defense.

In itself, this doesn’t necessarily rule out that the USPS may "establish and operate" PCCs for domestic purposes also. But this same document then goes on:

Appendix A, USPS-Department of Defense Postal Agreement: Definitions
…
Postal Concentration Center – A Postal Service facility at which military mail is concentrated for processing and delivery or dispatch.

Google Search: USPS "Postal Concentration Center" – even without clicking through any of the hits, the military connection seems clear from the snippet summaries.

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.