48 U.S.C. § 738 : US Code - Section 738: Free interchange of merchandise with United States

Search 48 U.S.C. § 738 : US Code - Section 738: Free interchange of merchandise with United States

All merchandise and articles coming into the United States from
Puerto Rico and coming into Puerto Rico from the United States
shall be entered at the several ports of entry free of duty and in
no event shall any tariff duties be collected on said merchandise
or articles.