The Hidden Pattern in Post Codes

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I absolutely love that the chaos of Ireland's post codes makes it super easy to add or remove addresses with absolutely no fuss, that's amazing

Ireland sometimes doesn't need the Eircode either. The An Post guy is such a boss that I've had mail arrive with just my name on it.

Fun Fact: The U.S. ZIp Code digit 9 actually extends *outside* of the United States, to Palau, Micronesia, and the Marshall Islands. The U.S. took control of these islands from Japan after World War II and even though they're now independent countries they are still served by the U.S. Postal Service and treated as domestic addresses for American shipping.

Mailman (city letter carrier) here, the "new" last 4 on the zip code are useless or more specifically obsolete, they became obsolete when we changed to the DPS (delivery point sequence) system, basically every address on a route has a delivery number, before that the last 4 helped narrow down a neighborhood, apartment complex, or other high volume mail area that extra sorting might help. But with DPS, the auto-sorting machines, and spraying of IMB (Intelligent Mail barcode) on every letter, the ZIP+4 has no purpose and if you look at the Zip+4 lists now, you can see something of time capsule of how routes used to be as the +4 was never updated to reflect route adjustments.

What Grey didn't expand on is that before adopting Eircode in 2015, Ireland didn't really HAVE post codes. So they took a system that sometimes relied on individually named houses in the address (yes, some houses had names instead of street numbers - and I guess some probably still do) and leapfrogged the rest of the world by adopting a 21st century solution. Good job Ireland!

Alright well I guess I'm gonna start writing my +4 on everything now just because it's peak efficient. Thank you Grey, very cool, the post office folks will be very pleased they no longer have to figure out my package routes when the code can do it for them

Back in the late 90's-early 00's when we still got video game demos on disc, there were often early game developer websites you could sign up to get free ones sent to you in the mail. They only let you order one per address, but I figured out that you could very lightly tweak or misspell things and the form thought it was a different address. Some of these demos I could resell for a few bucks so I set out to experiment and see out how much I could change my own address and still get the disc successfully. Turns out I could absolutely butcher the street, city, and state and even the house number sometimes and still get it to show up, but if any part of the zip was wrong, game over! Those never arrived

I love the postal service. You should do something about how international mail works. I've always wondered how the delivering postal service is compensated for the mail they deliver for other countries. Are there some sort of international agreements on it? How come usps has a single rate on letters to almost every country in the world? Surely some countries would demand more compensation than others?

We are SO back.

Given Japan's street address system. They should probably adopt Ireland's post code.

This inspired me to check the map of ZIP codes, which reminded me that there are a few _single buildings_ in Manhattan which have their own 5-digit ZIP code, like 10112 (30 Rockefeller Plaza, where SNL is filmed). What I found most fascinating was that none the four largest buildings in Manhattan by square footage (55 Water Street, MetLife, 1WTC, and 111 8th Avenue) have their own five digit ZIP code.

4:32 hey, that looks like a Dutch postal code... Wait a minute, it IS a dutch postal code!

2:48 Unfortunately (according to a quick google search) this is called a "Sectional center facility" (SCF), not a "Sectional facility center".
This, of course, doesn't matter at all.

Please, for the love of all that is good: in most (at least many) cases the ZIP+4 uniquely identifies your address. If you’re going to block out your address, also block out at least the plus 4.
As an example, someone shared an envelope, and blacked out their entire address except the ZIP+4, and after looking up that, I knew they lived in apartment number 14, because apartment 13 and 15 both had different ZIP+4s.

My big complaint is that I keep trying to do my ZIP+4 only to have web forms refuse to accept the extra four digits because whoever DESIGNED THE ORDER FORM is quite certain a zip code is only 5 digits

7:45 did not foresee this fall 🤣

I was in my mid-to-late teens when I stumbled upon this channel. I remember sitting down and binging everything you'd made, in chronological order. Your way of conveying information just resonated with me, in a way only my best teachers had managed. And I've stuck by, ever since.
Today I'm 31. The sheer nostalgic joy of a video coming out, is incredible.
If I could pick any person, to have a cup of coffee with, I'd pick you.

Took me a long time to realize the letter is addressed to Christopher Billop from the Staten Island video

Fun Fact: In Germany, from 1990 onwards, there was a four-digit postcode system. There was a problem: the postcodes often overlapped, for example 2300 was used for Stralsund and Kiel. There was a way to get around this: W (west) and O (east) were written in front of the number. That means O-2300 for Stralsund and W-2300 for Kiel. From October 24, 1991, the board of the German Federal Postal Service (today: Deutsche Post AG, or DHL Group for short) decided on a completely new five-digit system.

Fun fact, zip codes aren't actually required in the United States. They were introduced to make hand sorting faster but then we built machines that have a master list of every address in the country and the right zip code so they can figure it out automatically.
So we never actually got to the point of making the zip code mandatory for normal people. It doesn't comply with USPS's recommended practices but your mail should still get to it's destination.

As someone who has lived 90% of my life in New Jersey and Massachusetts, I always thought other states were weird for having zip codes that don't start with 0. Now I know the truth

was kinda hoping you would go into more countries postal code systems

Oh poor Grey... I can only imagine the rabbit hole that you went down to make this video and I love you all the more for it. Thank you again for tackling a complex topic and breaking it down with enough nuance to hint at the reasons for an imperfect system and how it came to be while also explaining it.

Gotta love the wild world of codes everybody has to live with but nobody understands

When mailing internationally... you probably should include the country. ON THE LAST LINE, below the postal code. Because the US sorters may not know a Canada post code from one in England. If the address ends 'Ontario, CA M5G 1X6', country before the postal code, your package *will* go on a trip to Ontario California.
Same applies to mailing things to the US, the country one line down from the zip - otherwise the sorters may wig out and ship our international mail back to Japan or wherever it came from.
Cheers.

I drummed my feet against the floor at a new CGP Grey video and this did not disappoint. I was entranced, I laughed, I cried. It was an epic compressed to 7 minutes. Perfection.

Oh this is awesome.
Ireland is btw killing it

CGP GREY IS ALIVE!?

It has been so long since last CGP Grey upload

Great video from famous notebook salesman CGP Grey!

So Ireland's postcodes are a bit like traditional postcodes and Plus codes / OpenLocationCodes combined. Smart!

Live in the uk, there's 2 houses on my postcode and I'm number 2 so postcode will work especially well with a house with a name and number whilst also not being number 2 on the road we live on :)

I've actually seen some comradery derived from post codes here in the UK ('the NE5 area' or such) so there's another advantage of not having things, just, random! I also met a cab driver who liked that he would know the general area of an address (in London) just by the postcode, since you often might not know the street.

I absolutely love how all the latest videos (latest being relative since we get one post a year lol), I have the immediate reaction of "who cares, this seems so dumb" since in my head I naturally default to comparing new videos to the ones of days passed like "Rules for Rulers" or the election series. But boy am I always wrong and end up watching the new video with a wide grin as Grey takes a video that shouldn't be interesting and makes me so gripped I could watch for hours.
I pray for new videos like "Rules for Rulers" since that literally changed how I viewed international policy and the world as a whole...but will still always enjoy these videos for the crazy rabbit holes that Grey subjects himself (and us) to!

In Germany the purpose of zip codes is in the name. We call them postal guiding codes (Postleitzahl) as it guides the post on how to get to the final post office.

Good to see you again !

0:22 France is "numeric"! We use 5 digit post codes!! How is this data not known?

Thanks!

Not gonna lie, I was grinning ear to ear when i saw the notification of a new video. :D

I bet after this video there will be a noticeable uptick in use of the last four digits by folks in the USA

I bet you loved using the new Minnesota flag on the stick figure’s skirt!

Postcode went a bit complicated in Germany after reunification, Imagine a country almost doubling in size. To keep most of the old numbering system they basically just added another number in front.

For multi-story apartment buildings, Ireland's postal code just gets you to the building, right? You still have to write apartment/unit information on the letter?

Do I smell some Bonnie Bee postal codes in other countries videos popping up soon?

I got distracted at the zero code, remembering the address of the PBS show Zoom!

Yesssssss! TY!

Rejoice! The wanderer has returned! 🍀

What's wrong with your thumbnails? Mostly in the older videos

1:50 I dont mean to be THAT person, but you forgot 94 lol (only noticed cause I live there)

Looking forward to the sequel to go over more countries’ postal codes

Thank God we got uk included was wondering if we were different to the us

Thanks!

I was thinking that Ireland's way might not work the same in Taiwan , we have too many apartments that have hundreds of unit inside.

During this dark week where we're hurtling faster than ever towards destruction from an uncaring (and now possibly Chinese) machine god, I did not know that I needed a CGP Grey video on postcodes. But it's exactly what I needed!

If you were to send 1000 letters to Irish postcodes, given you restrict it to one postal area in, say, central Cork, how many would be delivered?

Éirinn go Brách!

Rewatching already! Very nais

Just add a geohash for that mathematical perfection.

I want to move to Ireland now.

And then in Hungary just every city has their own post code but boom the capital has like 230 different ones...

this is so fascinating omg

Missed you Grey

Taking bets on how many people are gonna try sending random letters to the Irish post codes featured [real or not]

Is my resolution too low, or is the map accidentally orange above the Netherlands?

UPS still requires the zip code but doesn't use the same sorting centers, yes?

New grey is not the highlight of my day I was expecting. But it’s sooooo welcome.

In the Netherlands your mail will arrive with just the post code and the housenumber! (So I think ours superious to the UK's :) )

You mean the zip code isn't a good way to bundle population statistics based on land proximity? Data shock!

YESSSSSS NEW VID

Christopher Billopp, a British loyalist who lived on satterlee st on staten island during the US Revolutionary war 🤓

So back.

It was interesting living in Grenada - despite my best efforts I couldn't find a ZIP for that country

Hopefully now we can get an explainer on what caused the delays and can expect more vids in the future! Hope whatever the issue was was transitory and wishing you well, Grey.

The downside to Ireland's method is that if their electronic infrastructure breaks down, the databases become unusable or the automatic sorting machines won't work, then humans are going to have a hell of a time sorting all the mail by hand...
I'm a software engineer and I think it's incredibly dumb to make societal functions so heavily reliant on software that you cannot do the work by hand. Software should serve an assisting function, not be relied upon.

5:24 I think this is the first time, in a long time, that someone other than Grey spoke more than two sentences with their mouth OPEN
Dear lord Grey is evolving

1:07 I'm sure this was just for rhyming purposes, but the suggestion that Maryland and West Virginia are in any way part of the south hurts me a little as a native Marylander

I have to ask. at 0:22 what is going on in the middle east? Did I miss out on some Arab-Iranian Federation at some point?

I'm one of those weirdos that includes his +4 thank you very much.

Y'know, as a Midwesterner, I kind of like Old Northwest better

On my house title, the zip code is incorrect due to the kind of re-organization you mentioned at the end that changed its zip code.

CGP Grey in 2025?!

I'm becoming a post code perfectionist!!!

So today we learn that Ireland is based

Hes back do a video on illinois

Is that the Boulder Dash music?

Every Gray video is Yes but also as No

That's so crazy

perfeito

BABE WAKE UP, NEW CGP GREY VIDEO!!!

Thank you!
Can we have American $5 coins now?
Put Lincoln on them and then let go of the penny.

Neat

i'm too early

Hitting reverse at zero to hear Grey dropping the beat 🤣 Ery.. Ery.. Ery.. Ery letter!

Amazing, a video not about flags!

+

Yayyyyyy

+

Let’s go