Morris was born at or near Liverpool, England, in 1734. When he reached 13 years of age, he emigrated to Maryland to join his father, a tobacco exporter at Oxford, Md. After brief schooling at Philadelphia, the youth obtained employment with Thomas and Charles Willing's well-known shipping-banking firm. In 1754 he became a partner and for almost four decades was one of the company's directors as well as an influential Philadelphia citizen. Wedding Mary White at the age of 35, he fathered five sons and two daughters.