Duro Bag Mfg is the largest paper bag manufacturer in the world and produces paper bags for numerous companies in the US. Duro Bag Mfg was founded in Covington, Kentucky in 1953 by Mr. S. David Shor and is still a privately owned company.

Duro Bag is the only manufacturing facility at the Port of Brownsville that is non-maritime related. Charles Shor, who became President and Chief Executive Officer in 1987, ran the company started by his father until July 1, 2014. South Carolina-based Hilex Poly Co. LLC. acquired Duro in July 2014.

The Designer Division produces the broadest range of machine-made paper shopping bags in the industry. The variety of applications includes Retail, Resale, Restaurant/Food Service, and Medical/Pharmaceutical. Duro has purchased some of its larger competitors in order to expand its geographical reach and enhance the company's production capabilities.

Duro Bag has over 1,800 employees working at 11 facilities across the country, with the corporate office located in Northern Kentucky.

According to en.wikipedia