NY 9G initially extended from Rhinebeck to Hudson when it was assigned as part of the 1930 renumbering of state highways in New York.

NY 9G is maintained by the New York State Department of Transportation (NYSDOT) outside of the cities of Poughkeepsie and Hudson.

[3][4] The highway starts at a junction with US 9 at Marist College and Saint Francis Hospital in the Dutchess County town of Poughkeepsie.

Past CR 40A, it runs parallel to the Eleanor Roosevelt National Historic Site while it travels west of the Union Cemetery.

The route crosses its parent, US 9, north of the village center, at which point it enters the Hudson River Historic District.

It crosses over Roeliff Jansen Kill on its way into the town of Greenport, where it meets NY 23 at the eastern foot of the Rip Van Winkle Bridge in a highly channelized junction adjacent to the Olana State Historic Site.

[5] NY 9G was assigned as part of the 1930 renumbering of state highways in New York; however, it extended only from US 9 in Rhinebeck to US 9 in Hudson.

[11][12] In Hyde Park, the former alignment of NY 9F along Market Street remained state-maintained until April 1, 1980, when it was transferred from New York State to Dutchess County as part of a highway maintenance swap between the two levels of government.

A group of legislators is currently working on improving safety of the road between Bard College and Germantown.