As the highway leaves the Watertown area, it passes into another area of rolling, open terrain with only pockets of development in the immediate vicinity of the road's interchanges. NY 37 largely replaces US 11 as the paralleling surface route, and the state route follows I-81 for to the vicinity of Theresa. West of the village, I-81 intersects NY 411, a connector between La Fargeville and NY 37. While NY 37 continues north from Theresa, I-81 turns to the northwest, crossing increasingly isolated areas of the state to reach NY 12 on the south shore of the St. Lawrence River midway between Clayton and Alexandria Bay. From here, the freeway heads into the Thousand Islands on the first of several bridges known collectively as the Thousand Islands Bridge.