 After 1763 the trade came to be controlled by British firms, although many of the traders were men of French descent, although a growing number were Metis.The North West Company was particularly influential in the city, as it built an office and warehouse there circa 1805.In 1816, however, a new U.S. Law blocked foreign participation in the fur trade within the Louisiana Territory, greatly limiting British and Canadian firms' roles in the Mississippi River trade.