Most classic American selvage denim was produced on looms made by the Draper Northrop Corporation in Hopedale, Massachusetts.
Their looms boasted features like an automatic bobbin change, which allowed an operator to oversee more looms than was possible than the ‘Hand Looms’ produced by rivals such as Whitin.
After their introduction in 1894, Draper automatic looms soon became the industry standard, in versions such as the Model E, and the later X series.
Their last common selvage loom was the X-3, which was capable of producing denim in 60 inch width (which explains why visible selvage is less common on jeans from the 1950s onwards).
Despite marketing spiel that high-end Japanese denim is produced on “Old Levi’s” or “Old Draper” looms, there is no evidence that American looms are used for production in Japan.
Source: Paul Trynka