NY 9J begins at an intersection with
US 9 in the
hamlet of Columbiaville, located within the town of
Stockport. The route proceeds northwest along a two-rural street that parallels US 9 until the intersection with Day Road, where it turns westward. Reaching the
Amtrak and
Norfolk Southern's
Hudson Subdivision, NY 9J and the tracks begin a northward trek near the
Hudson River, winding past a junction with
County Route 46 (CR 46) in the town of
Stuyvesant. Winding northward along the tracks, NY 9J reaches the hamlet of Stuyvesant, where it intersects with
CR 26A (Kinderhook Street), a highway formerly designated as
NY 398. NY 9J continues north out of the hamlet of Stuyvesant, paralleling, crossing then paralleling a spur of the railroad tracks north of town. Retaining its northerly direction, the route parallels the
Muitzes Kill and past
Schodack Island State Park (composed of what was six islands now reduced to two). A short distance northward, NY 9J crosses into
Rensselaer County and enters the town of
Schodack. Immediately entering the hamlet of Schodack Landing, the route remains a two-lane residential street, crossing a junction with the western terminus of
CR 2 (Schodack Landing Road). Just after crossing the intersection with Knickerboxer Road, NY 9J crosses under the
New York State Thruway's
Berkshire Thruway and the
Castleton-on-Hudson Bridge. Past the Thruway crossing, NY 9J turns northeast, crossing Muitzes Kill and intersecting
CR 1 (Muitzes Kill Road) on the river's north bank. At this point, the road becomes known as South Main Street as bends northward into the village of
Castleton-on-Hudson. Crossing north through the village, NY 9J parallels the Norfolk Southern tracks to an intersection with the western terminus of
NY 150 (Scott Avenue). The route continues through Castleton-on-Hudson's northern portion as North Main Street before leaving the village for more rural areas along the banks of the Hudson River. It continues northeast along the riverbank as River Road to Stony Point, a small hamlet north of Castleton-on-Hudson, where the route connects to
CR 8 (Stony Point Road). Not far from Stony Point, the route crosses into the town of
East Greenbush, a suburb of the city of
Rensselaer. It intersects
CR 58 (Hayes Road) in the southern part of town before heading into heavily industrialized areas near the southern edge of the Rensselaer city limits. The route passes east of an
oil refinery for
Sunoco as it enters Rensselaer, where NY 9J serves several other commercial and residential buildings along a stretch leading to an interchange with US 9 and
US 20 (Columbia Turnpike). NY 9J feeds directly into the ramps to and from US 9 south and US 20 west while access to and from US 9 north and US 20 east is made by way of South Street, which connects to NY 9J just south of the interchange. ==History==