Hacker News Reader

Comment by Symbiote | Hacker News Reader

> mail with just a name and zip code tended to get to its destination

Is that unexpected? In Britain a (real but random) address like

  36
  B30 1QR

is sufficient. This format is most useful for a return address. Adding the street name would be helpful to the postman.

Addresses that receive a lot of post usually have their own postcode. "SW1A 2AA" is a minimum complete address for a letter to the Prime Minister's office (10 Downing Street).

View on HN

The US has a standard similar to that (we call it 'ZIP+4': a 4-digit addition to the earlier 5-digit ZIP code standard) but it didn't catch on in casual use. My ZIP+4 only contains a handful of addresses on my street. A street number and the ZIP+4 would be plenty enough to get a letter to me.

Institutional senders will usually use the ZIP+4 standard, but someone sending a letter in the mail typically will use the shorter 5-digit zip. Most people do not memorize the '+4' portion of their ZIP code.

My 5 digit zip code has about 8,000 addresses in it.

I'm aware that "house number + postcode" is often sufficient to uniquely identify a property -- it works for my house, for example -- but I've wondered if this is always the case. When I enter a postcode into my satnav, it sometimes offers a choice of several street names, which seems to imply there might be duplicate house numbers within the single postcode. But I've never tried to confirm this -- do you know?

Not always. At my old postcode someone had recently built a block of flats not quite large enough to get its own postcode. The postcode also contained an older block of flats and some houses. We were flat 9 but the postcode contained two flat 9s and a house number 9.

It's not always correct, no.

Fortunately there's another identifier - the Unique Property Reference Number (UPRN) - that exists to, well, uniquely identify every property in the UK.

Currently it's proprietary but from July 2020 it will be available for use under the Open Government License.[0]

[0] https://mhclgdigital.blog.gov.uk/2020/04/02/unique-property-...

By "number" I meant "name or number", since some buildings don't have a number. A flat number is obviously also necessary if applicable.

A previous discussion on this, in 2013, tried to give some examples. None of them seem to break the rule, since "Pleasant Cottage" and so on are building names. If there's a counterexample, Wikipedia should be updated.

https://news.ycombinator.com/item?id=5625027

In the US, that's actually kinda surprising to me. Even in the suburb where I grew up, where there's no obvious overall grid system and instead the streets tend to meander around, parallel streets in the same neighborhood tended to share a lot of numbers.

I think they are giving all houses a number now, most houses around me (south west uk) have a name and a number now, where they all used to have names.

My house has a number, but for some reason it's listed under the "name" of my house - no end of confusion.

Yes I had an address that had a duplicate.

I think the other address was supposed to have an East before the street name, but when they left that off I got (some of?) their mail.

Should have figured out my +4 and tried that.

The UK postcode system is not some magic hash that can resolve to a street name. Instead it’s a database maintained by Royal Mail that’s updated when a new postcode or street is created. This would explain why your sat-nav doesn’t know about newer addresses as its database hasn’t been updated.

In the US, we have ZIP+4, which appends an additional four digits to the five-digit ZIP code. It's mainly used by bulk mailers, as part of qualifying for reduced postage rates.

Like the British postcode, important addresses have their own ZIP+4. E.g., 20500-0001, 20500-0002, and 20500-0003 refer, respectively, to the President, the First Lady, and the White House in general.

yes when I was in London i always wondered why everyone was obsessed with putting postcodes in on Google Maps (rather than the street), till i realized how accurate it was in locating an address.

5 digit US zip codes are pretty course, thousands and thousands of people each.

The newer 9 digit codes are something like the delivery route for the address (I'm not sure that is exactly right, but they are much finer grained).

Putting just my house number and ZIP code into Google maps just got me the outline of the ZIP code area. Using just the ZIP and ZIP+4 didn't improve the results. Google doesn't quite know everything yet. ;)

You should have gone with:

Willy Wonka, Chocolate Factory, B30 1JR

Reply on news.ycombinator.com