For knit apparel, CBP generally applies a 'substantial transformation' test, with the knitting operation — where yarn becomes fabric and garment form — typically considered the transformative step that confers origin. If yarn from one country is knitted into a garment in a second country and finished in a third, the country where knitting occurred is usually the country of origin for duty and marking purposes.

Yes — the Textile Fiber Products Identification Act requires that knit garments bear a label disclosing fiber content by percentage, country of manufacture, and the manufacturer's or importer's identity (RN number or name). The FTC enforces these labeling rules, and non-compliant goods can be detained at the border or subject to recall after entry.