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 Parkway Thousand Islands Bridge. It continues northeast, serving the riverside communities of Darlingside, Rockport, Narrows, La Rue Mills and Mallorytown Landing. At Butternut Bay, the Thousand Islands Parkway merges into Highway 401 eastbound and a left-hand exit provides access to the parkway from westbound Highway 401. Throughout most of the length of the parkway, a recreational trail parallels to the north. The Thousands Islands Parkway follows what was the original alignment for Highway 401. However, because of the residential properties and the scenic nature of the route, a new inland route was constructed through the mid-1960s. The recreational trail follows the