Thousand Islands level year-round, and support at least two living trees. The Thousand Islands archipelago is located at the outlet of Lake Ontario at the head of the Saint Lawrence River. The region is bisected by the Canada–United States border and covers portions of Jefferson and St. Lawrence counties in the U.S. state of New York, in addition to parts of the United Counties of Leeds and Grenville and Frontenac County in the Canadian province of Ontario. Geologically, most of the islands are located where a branch of the Canadian Shield runs south across the river to join with the Adirondacks. The
Thousand Islands Bridge corporation, whose seven board members are appointed by the Jefferson County Board of Legislators. Four board members are US citizens and three are Canadian citizens. The Thousand Islands Bridge Authority also maintains and administers Boldt Castle. Tolls are paid only by cash, or with a Commuter Discount Fare Card, which is good for either 16 trips (US$20.00) or 72 trips (US$32.00). No electronic toll collection transponders are currently offered or accepted, although the Bridge Authority has joined the multi-state E-ZPass consortium and was planning to introduce ETC in 2019. The Bridge Authority offers sales of transponders of Florida's SunPass, for