Deferiet is a village in Jefferson County, New York and was named after settler Jenika de Ferriet. It is located at the southwestern side of the town of Wilna and is east of Watertown and south of Fort Drum. Local businesses include Heims Auto Care Incorporated and Carthage Area Hospital DR Wiley Clinic. Jefferson County was named after Thomas Jefferson who was serving as the third president of the United States when the county was created in 1805. Jefferson County borders the St. Lawrence River and contains part of the Thousand Islands which straddle the US and Canadian border. The island chain stretches over 50 miles of the St. Lawrence River. The islands are a vacationing paradise offering boating, hunting, fishing, camping, restaurants and shopping.