The Leavitt family were merchants, shipowners and shipmasters, resident in Saint John, New Brunswick. Jonathan Leavitt (1746-1811) came to Saint John from New Hampshire in 1762 and was one of the first English-speaking inhabitants. He served as captain and pilot on vessels belonging to the firm of Simonds, Hazen and White prior to the American Revolution. Jonathan married Heprabeth Peabody and they had eight sons and two daughters. Jonathan's brothers Daniel and Francis joined him in Saint John where they were involved in the coastal trading as partners of Francis Peabody until 1810. Jonathan prospered as a shipowner and mariner and upon his death left a considerable estate.

Jonathan Leavitt's son, Thomas (ca. 1795-1850) continued the family business. He inherited a half-interest in the family home, ownership of four choice lots in Saint John, as well as a seventh part of a large landholding on the Miramichi River. In 1817, Thomas was admitted as a merchant freeman in the city of Saint John and from that time played an active role in the business life of New Brunswick. In 1822, he married Mary Ann Ketchum and they had four sons and three daughters.

In the 1830s and 1840s, Thomas acted as agent for the Liverpool Association of Underwriters along with a number of New York marine insurance companies. In 1835, he was appointed the US consul for Saint John. He was a founder of the City Bank (1837) and later, president of the Bank of New Brunswick. Thomas Leavitt died 24 October 1850.