The two short sides (usually 4 feet) are not wrapped. Sheetrock is drywall. USG (United States Gypsum), the manufacturer of ...

USG develops innovative building and manufacturing solutions, enabling global customers to efficiently and affordably create sustainable and accessible spaces. USG's range of durable Drywall ...

So USG sales representative D.L. Hunter suggested a re-brand to Sheetrock. One hundred years later, that term has become so ubiquitous that many people use "sheetrock" to mean any kind of drywall.