[ninju]

That because Excel defaults to treating numeric data as a number and leading zeros are extraneous and it will strip them off before storing the value (and it will right justify the display).

The root issue is that zipcodes though numeric in content (at least in the US) should not be treated as number (data type) but instead as a text (string) value

To tell Excel to treat this numeric data as a string you to either

* Precede the value with a single quote (') - Excel will treat the rest of the data as a string (and won't hide the leading zeros)

* Before entering the value set the format to TEXT which will tell Excel to take the entry verbatim with no inferring what the data represents (i.e. a number or date)

[magicalhippo]

And instead of just copy/pasting tabular data, use the Text Import Wizard (my translation) under the Paste drop-down menu, and ensure appropriate columns are marked as text.

[mattigames]

It is the fault of zip codes, they should have been prefixed with the state code from the start (CA for California and so on), that's one of the reasons secret 2FA codes are sometimes preceded with one or two letters (e.g. Facebook uses FB)

[windhaven]

The issue with that is that ZIP codes don’t map physical locations, they map the hierarchy of how the mail system does routing down to each post office and were introduced in the 1960s [0].

As a result, doing something “from the start” wouldn’t involve baking in comparability with the quirks of a piece of software written decades later, and you’d also have issues with, for example, single zip codes spanning multiple states.

[0]: https://en.m.wikipedia.org/wiki/ZIP_Code

[mattigames]

Well, then something that made more sense, like the letter Z for zip code.

[johngladtj]

Leading zeros are not extraneous and should not be removed though

[ziml77]

For numbers they are extraneous, for strings of digits they are not.

[wruza]

They are never extraneous, cause no automatic calculation process produces them. If they are there, it's intentional.

[otikik]

Aren't they exactly the definition of "extraneous"?