On recently manufactured men’s dress and dress-casual shirts, the bottommost front buttonhole often runs sideways, while all the others are up-and-down. Why is that?
The bottom buttonhole is the most likely to be stressed sideways (on a correctly-fitting shirt), and a horizontal 'hole takes the strain better, but doesn’t look as smart (or it would be used for all).
As I understand it, the bottom buttonhole on men’s shirts is typically different than the rest because the placket is made separately from the shirt itself, and then sewn on. Therefore the non-standard bottom button makes it easy for the line worker to quickly orient the placket correctly.
That doesn’t necessarily conflict with Malacandra’s response, although you also often see bottom buttons that aren’t horizontal but are marked in other ways, such as being trimmed in a different colored thread.
–Cliffy
My understanding about vertical buttonholes was that they were faster to mass-manufacture - is that not the case?
It could be so, but pyjama jackets (jackets and overcoats generally UIVMM) have horizontal buttonholes anyway - similar reasoning, I’d guess.