NY 320 begins a half-mile north of the Norwich city limits at an intersection with NY 12 in the town of Norwich. The highway heads to the northeast as a two-lane road, serving a commercial area along the southern edge of Lt. Warren Eaton Airport. It crosses over the Chenango River and a grade crossing with the New York, Susquehanna and Western Railway prior to intersecting CR 32. Past the junction, the commercial establishments give way to homes as the route continues to head away from the Norwich area. Near the eastern edge of a valley surrounding the Chenango River, NY 320 briefly turns eastward, running along the Norwich–North Norwich town line and crossing over Thompson Creek, a tributary of the Chenango River. After a quarter-mile, NY 320 curves back to the northeast and fully enters North Norwich. The route loosely parallels Thompson Creek as it runs uphill from the Chenango River valley, passing gradually fewer homes as it ascends in elevation. Eventually, the residences are replaced by farms as the road reaches a rural intersection with Tiffany Road. At this point, ownership and maintenance of NY 320's right-of-way shifts from the New York State Department of Transportation to Chenango County. The change in jurisdiction marks the eastern terminus of NY 320, and the state road's right-of-way continues east to a junction with NY 8 and NY 80 in the village of New Berlin as CR 29, which that route ends at the New Berlin village line and becomes a local road before ending at that intersection.
History
On October 22, 1907, the state of New York awarded a contract to reconstruct what is now NY 320 to state highway standards to the Newport Construction Company. Construction commenced on April 2, 1908 under the charge of engineer H.W. Benkhart. The new road would be constructed as a wide macadam road. This new road would be constructed with of macadam from local quarries followed by limestone from Oriskany Falls in Oneida County. The road cost $35,518 to rebuild, and it was added to the state highway system on October 15, 1908, as unsignedState Highway 597. In the 1930 renumbering of state highways in New York, hundreds of state-maintained highways were assigned a posted route numberfor the first time. One of these was SH 597, which was designated NY 320. The route's alignment has not been substantially altered since that time.
