It blows our hivemind that the United States doesn't use the ISO 216 paper size standard (A4, A5 and the gang).
Like, we consider ourselves worldly people and are aware of America's little idiosyncrasies like mass incarceration, the widespread availability of assault weapons and not being able to transfer money via your banking app, but come on - look how absolutely great it is to be European:
The American mind cannot comprehend this diagram
[Diagram of paper sizes as listed below]
ISO 216 A series papers formats
AO
A1
A3
A5
A7
A6
Et.
A4
Instead, Americans prostrate themselves to bizarrely-named paper types of seemingly random size: Letter, Legal, Tabloid (Ledger) and all other types of sordid nonsense. We're not even going to include a picture because this is a family-friendly finance blog.
Letter paper (8.5" x 11" | 215.9mm x 279.4mm) is kinda sorta pretty close to A4 (8.27" x 11.69" | 210mm x 297mm) so without having the two next to each other, it can seem like A4 is just a funny piece of letter, and vice versa. But to answer the actual question, USA and Canada (and apparently the phillipines???) use the "North American Standard" which is a terrifying mess in comparison to the beauty that is the ISO standard.
America tried to modernise many British means of methods and standards. They used a metric currency long before Britain. That’s why they have a cent (1/100) rather than pennies and bobs and truppence.
They got ride of many terms for multiples of measurements that made the imperial system more similar to metric. Americans use ounces, but they don’t use pounds.
America also defines their us customary units using metric. There’s no longer an inch. There is a meter and from that an inch is defined as 24 millimeters. This is largely due to British, Canadian and American components for fighting wars not fitting together despite all using the same inch.
Had America modernised a little later they probably would have converted to metric earlier than Britain.
Tbf, I can see the use case for some "non-standard" sizes, like Legal, where having more height to the page without the extra width might be useful for readability of long documents.
And always fractional, so, to convert from Farenheit to Celsius (inferior to kelvin, though), you take farenheit, add 57 mice, and divide by a hamburger.
As a European, haven't you heard about the existence of the B and C series of paper sizes? It may not be exactly what you have in mind, but B4 paper is 250 x 353 mm (9.8 x 13.9 in) and C4 paper is 229 x 324 mm (9 x 12.8 in). There's also elongated A which is really long.
I hope you appreciate the irony of an American telling you about them.
Filofax If from UK. For these organisers and notebooks they produce, imho it actually makes sense to have several (equally spaced) holes.
Swedish Triohålning and especially the corresponding binders however, are mildly speaking impractical: It works starting from ISO A6 instead A7 and reading documents in a trio binder is a mess.
11x17 is incredibly common too. Usually it is oriented landscape and z folded to get a large diagram into a document. It's kind of irritating that the most typical large format size is 24x36, which is a different aspect ratio than 11x17, for a variety of reasons. If you're designing something you need to know what aspect ratio to design for. Most copiers can do 11x17, and if the standard large format size was 22x34 it would be exceedingly easy for most offices to produce good working copies of large documents. Best compromise I've seen is when people put a logo or header on the side that can be omitted when you switch aspect ratios.