Columbia County NY 66 begins at an intersection with
US 9 and
NY 23B (Green Street) in the center of the city of
Hudson. Proceeding northeast along Union Turnpike, NY 66 becomes a two-lane city road through Hudson, soon leaving for the town of
Greenport, where it becomes a two-lane commercial street north of the city. Retaining its northeastern direction, the route crosses over the Claverack Creek and enters the town of the same name. The route passes the Dutch Village
mobile home park and several residences before reaching an intersection with
County Route 18 (CR 18 or Fish and Game Road). After CR 18, NY 66 becomes primarily rural in nature. Entering the hamlet of
Brick Tavern, NY 66 reaches a junction with
NY 9H in the southern end of the hamlet. NY 66 continues northeast through the town of Claverack, reaching the southern terminus of
CR 20 at the eastern end of Brick Tavern. Passing south of
Columbia County Airport, the route passes the junction with former CR 20, crossing into the town of
Ghent. Continuing northeast, NY 66 remains rural in nature, soon reaching a junction with
CR 9 (Mellenville Road). NY 66 reaches the hamlet of Ghent, where it meets a junction with the southern terminus of a section of
CR 21 (Church Street). Continuing out of Ghent, NY 66 crosses over an abandoned
railroad grade and a junction with another section of CR 9 (Arnolds Mill Road). At CR 9, NY 66 turns north through the town of Ghent, reaching the hamlet of Buckneyville. The two-lane roadway remains rural for this portion but the road crosses into the village of
Chatham, where it gains the moniker of Hudson Avenue. Crossing through a residential section of Chatham, NY 66 reaches a junction in the eastern end of the village with
NY 203 (Church Street / Coleman Street). Passing the Chatham Rural Cemetery, NY 66 enters the Depot Square, where it passes
Chatham's New York Central Railroad station. Passing the station, NY 66 also has a junction with the terminus of
NY 295 (Railroad Street). Now known as Main Street, the route remains commercial through the northern reaches of the village, turning northwest at a
roundabout with Austerlitz Street, River Street and Kinderhook Street. Continuing onto Center Street, NY 66 winds across the northern reaches of the village before crossing into the town of
Chatham, where it drops the Center Street moniker. Through the town of Chatham, the route returns to its rural nature, passing a junction with a former alignment of NY 66 that dead-ends in the nearby woods. Turning northwest again, NY 66 enters the hamlet of Old Chatham, where it reaches a junction with
CR 13 before crossing
Kinderhook Creek. After crossing Kinderhook Creek, NY 66 reaches a junction with
CR 28. Just north of the hamlet, the route turns northeast at a junction with
CR 17. Winding along Kinderhook Creek, NY 66 turns northward near Spangler Road, remaining a two-lane rural roadway. Continuing northward, the route crosses under the
Berkshire Thruway section of the
New York State Thruway (
I-90). After a junction with the eastern terminus of
CR 32, NY 66 turns northeast into the hamlet of
Malden Bridge, reaching a junction with Albany Turnpike, where NY 66 turns southeast and re-crosses Kinderhook Creek. After crossing Kinderhook Creek, NY 66 turns northeast and out of Malden Bridge, reaching the hamlet of Riders Mills, a rural community alongside the creek. Less than a mile north of Riders Mills, the route crosses the
Rensselaer County line and leaves the town of Chatham for the town of
Nassau.
Rensselaer County Now in the town of Nassau, NY 66 continues northeast along Kinderhook Creek, soon reaching a junction with
US 20. Continuing to parallel Kinderhook Creek, US 20 and NY 66 form a
concurrency through Nassau, passing several former alignments of US 20 before crossing over the creek twice. Rapidly approaching the
Columbia County line once again, the routes reach the residential hamlet of
Brainard, where they meet the northern terminus of
CR 19, a short connector the aforementioned Columbia CR 13. Just east of this junction, NY 66 forks north off US 20 and continues north along Kinderhook Creek as it enters the village of
East Nassau. In the center of East Nassau, NY 66 reaches a junction with the terminus of
CR 26 (Garfield Road). Near the junction with Tsatsawassa Lake Road, NY 66 leaves Kinderhook Creek behind permanently, continuing north through the town of Nassau, past
Tackawasick Lake and the
Tackawasick River before reaching the hamlet of Hoag Corners, where it reaches a junction with
CR 16 and
CR 21 (Dunham Hollow Road). Crossing the Tackawasick River, NY 66 continues north out of Hoag Corners and past Pikes Pond. At the northern end of Pikes Pond, NY 66 reaches a junction with
CR 20 (Totem Lodge Road). Just north of that junction, the route enters the hamlet of Denault Corners, where it meets with
NY 43. Now concurrent, NY 43 and NY 66 continue northwest through Denault Corners as a two-lane residential street as it crosses into the town of
Sand Lake. The routes run northward along the eastern shores of
Crooked Lake and past a junction with
CR 49 (Eastern Union Turnpike). Soon Crooked Lake gives way to
Glass Lake, which is bordered with lakeside homes near NY 43 and NY 66. Just before crossing Glass Lake Road, the routes turn northwest again, crossing into the hamlet of Sand Lake, where they reach a junction with
CR 42 (Taborton Road). At this junction, NY 43 forks to the west, while NY 66 continues northwest out of Sand Lake as Miller Hill Road. Crossing northwest through the residential section of Sand Lake on Miller Hill, NY 66 soon leaves the town of Sand Lake for the town of
Poestenkill. Along this northwestern stretch, NY 66 drops the Miller Hill Road moniker, crossing a junction with
NY 351 (Reichards Lake Road / Round Top Road). A short distance after NY 351, the route returns to the rural nature it once had, crossing a junction with
CR 68 (Snyders Corner Road). Winding northwest past a large
quarry, NY 66 reaches the western terminus of
NY 355 as it enters the town of
North Greenbush. Now known as Main Avenue, NY 66 crosses into the hamlet of
Wynantskill. Through Wynantskill, NY 66 becomes the main two-lane west–east street through the community, passing Evergreen Cemetery and a junction with the northern terminus of
NY 150 (West Sand Lake Road). Remaining a two-lane commercial street, NY 66 continues west along Main Avenue along the Wyants Kill before leaving North Greenbush for the city of
Troy. Upon entering Troy, NY 66 crosses the southern terminus of
CR 142 (Mountain View Avenue). Passing through the
Albia section of Troy, the route runs northwest along Pawling Avenue, remaining a two-lane residential street for a distance through Troy. At the junction with Pinewoods Avenue and passing south of Ida Lake, NY 66 turns north past Mount Ida Cemetery and crosses the Poesten Kill before reaching a junction with
NY 2 (Congress Street). This junction marks the northern terminus of NY 66 just south of the
Rensselaer Polytechnic Institute and southeast of downtown Troy. ==History==