After crossing the county line, NY 203 crosses under the Berkshire Spur of the New York State Thruway (I-90) in the town of Nassau. Beyond the Thruway, NY 203 continues northward, crossing and re-crossing the Valatie Kill.
Following the county line, NY 203 descends under the Berkshire Spur of the New York State Thruway (I-90) in Nassau town. Beyond the Thruway, NY 203 proceeds northward, crossing and re-crossing the Valatie Kill.