New York State Route 104A (NY 104A) is a northeast–southwest (signed as north–south) state highway in the central portion of New York in the United States. It serves as a northerly alternate route of NY 104, to which it connects at each end. The route extends for from an intersection with NY 104 and NY 370 south of the village of Red Creek to a junction with NY 104 southwest of the city of Oswego. NY 104A spans three counties, serves two villages (Red Creek and Fair Haven) and parallels Lake Ontario for much of its length. All of NY 104A is part of the Seaway Trail, a National Scenic Byway.