Information in my database include: John Duart, b. 1784 in Hillsborough, County Down, Northern Ireland immigrated to Canada, married to Jane Hicks and their family and descendants. Additional Scot-Irish Duarts living in the United States and elsewhere: Robert Dewart from Hillsborough, County Down, Northern Ireland. Sarah Duart born abt 1808 in Ireland who married James Greer, lived in Cavan, Ontario Canada.
John Duart is found in New York City where he registered for the War of 1812, that was required of British citizens in the United States at the time.
It is said that the immigrant, John Duart worked as a stone mason and helped build the main tunnel used by the New York City Water-works (I have not been able to confirm this); he lost his health while engaged in working on that tunnel, and died in 1823, in his fortieth year. His son, D.H. (David Henry) was a native of York, Canada West (now Toronto, Ontario) moved to Towanda, Pennsylvania in 1837.