Now in Potsdam, NY 310 retains its rural nature, winding northward through an intersection with CR 34, which connects to the hamlet of Bucks Bridge. Now running in distance of the Grasse River, NY 310 leaves the town of Potsdam for the town of Madrid. Crossing over tracks for the New York and Ogdensburg Railway, NY 310 enters the hamlet of Madrid and becomes a two-lane residential road for two blocks, intersecting with NY 345. After NY 345, the route leaves the Madrid hamlet with the new moniker of Madrid–Norfolk Road, winding northeast along the Grasse River as a two-lane rural road in Madrid.