why do we need to use city and state in our addresses if ZIP codes are already linked to the city and state?
In: 100
From other comments it seems zip codes are mapped out different to UK post codes, but over here I can put just the house number and post code (37, AL9 4QA) and the mail will be delivered.
For simplicity sake let’s say the zip code is 100, and there are 3 towns that use the same zip code. The problem raises, when 2 of those towns have street named “center street” or something, now you have same zip code and 2 different street in different locations. So you don’t know does the post go to town A or town B, unless it has enough information to pinpoint the exact location of the delivery.
I wish I could just enter my zip+4 (9 total digits), which is my exact address instead of entering all the other stuff.
When I was little my grandma sent us a letter and it had NSW instead of Vic as the state both states have the same suburb, but since she wrote the right postcode we got it.
I guess it’s a foolproof tool, if something is off the other details can be used. Wrong state check the postcode, wrong postcode check the suburb and state etc.
You could **mostly** get away with it – with emphasis on MOSTLY
Zip codes are designed for mail delivery and making the mailman travel less, so there is no guarantee the same zip code does not include multiple towns. There are in fact [93 zip codes](https://gis.stackexchange.com/questions/53918/determining-which-us-zipcodes-map-to-more-than-one-state-or-more-than-one-city) **where a zip codes even spans different states**
There is also the case where people accidentally swap digits in the zip code, **so 65465 becomes 65456**, and now you letter goes to the completely wrong place if you didn’t provide some backup information.
Then there is also the “fakes”, and if you have ever delt with online user databases, you would know that the [most popular zip code](https://spectrumlocalnews.com/nys/capital-region/news/2015/09/18/sorting-fact-from-fiction-in-schenectady) to use is **12345** – now that is an actual valid zipcode, but there are only a few 1000 people living there and there are million of register online users.
I lived in a city that shared a zip code with another city, so it was really unreliable to have these two based only on zip. Example 48183, this is woodhaven Michigan as well as Brownstown Michigan, depending where you lived as well.
I cant give a complete answer, but I’ll try to add my knowledge on to what other people have said.
I’ve done programming that interacts with taxing softwares (so that your order can be taxed correctly based on your location). Zipcode != city and state. Hell even Zipcode+4 with city and state does not give unique tax results. It could depend on if you are in a incorporated or unincorporated area.
edit: And by god I only know some of this because we’ve have people call in to complain about the tax calculations. My favorite was the dude who called in complaining so much it got escalated to me (a programmer). And yes, I did determine his taxes were wrong! They weren’t high enough, so I fixed that for him for that month and every month going forward.
Not an explanation really, but the amount of people who put the wrong zip code when they order things might surprise you.
Where I work, we use the city/state to find the correct zip code or else the system won’t upgrade the order to invoiced.
It’s a good question. In the Netherlands your postcode links to your street. So the minimum you need is your postcode and house number. Makes filling out webforms really fast.
In the US, it seems to be more for back up. But in the Netherlands, for example, postcodes (Dutch for zip codes) are actually really well organised.
A Dutch postcode consists of four numbers and two letters. And the way they set it up means that every combination of postcode and street number (not name) is unique. So if you want to enter your delivery details in a website, a well organised website will only ask you for your postcode and street number, and it’ll enter your street name and place name for you.
PostNL also sorts mail by postal code. Every post box has two slids: one for local mail, and one for less local and international stuff. And you can even order codes nowadays you write on your envelope so you don’t have to buy a stamp, though the price is roughly the same.
If you want to play with this, here’s a good website: https://postcode.tech/
*Corrected the postcode syntax.
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