It was extended north to Troy as part of the 1930 renumbering of state highways in New York and rerouted south of Ghent to serve Hudson c. 1933.

NY 66 continues northeast through the town of Claverack, reaching the southern terminus of CR 20 at the eastern end of Brick Tavern.

NY 66 reaches the hamlet of Ghent, where it meets a junction with the southern terminus of a section of CR 21 (Church Street).

[4] Continuing out of Ghent, NY 66 crosses over an abandoned railroad grade and a junction with another section of CR 9 (Arnolds Mill Road).

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.

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.

Winding along Kinderhook Creek, NY 66 turns northward near Spangler Road, remaining a two-lane rural roadway.

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.

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).

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.

This junction marks the northern terminus of NY 66 just south of the Rensselaer Polytechnic Institute and southeast of downtown Troy.

[9] NY 66 was altered c. 1933 to follow Union Turnpike southwest from Ghent to Hudson, bypassing Claverack and Philmont to the west.