the Athens–Hudson ferry shut down in the late 1940s. NY 23 utilized modern NY 23B between the bridge and Hudson. Plans were made in the early 1950s to construct a southern bypass of the city of Hudson between the Rip Van Winkle Bridge and NY 23 midway between Claverack and Hollowville. Construction on the portion of the highway between the bridge and US 9 south of Hudson began in the mid-1950s and was completed in the late 1950s as a realignment of NY 23. Ultimately, this was the only section that was built; as a result, NY 23 overlapped with US 9 and NY 9H to reach its former alignment in Claverack. NY 145 was extended eastward along NY 23 from Cairo to Catskill . Both routes were realigned in the 1960s to follow a new arterial between Cairo and the Rip Van Winkle Bridge in Catskill. The first segment of the highway, a northerly bypass of the hamlet of Cairo, opened . The remainder of the arterial was completed in the mid-1960s. NY 145 was truncated back to Cairo on January 1, 1970. Much of NY 23's former routing between Cairo and the Catskill village line is now CR 23B; however, a segment in Jefferson Heights between exit 21 of the New York State Thruway and a town road named Austin Acres is state-maintained as NY 911V, an unsigned reference route. In Oneonta prior to the construction of the James F. Lettis Highway and I-88, NY 23 crossed the Susquehanna River concurrent with NY 28 along current NY 992D. In July 1984, NY 23 was realigned west of North Pharsalia to follow a new highway between NY 26 in Cincinnatus and North Pharsalia. The length of the Chenango County portion of the new alignment was , roughly double that of NY 23's old routing (). The of state highway mileage for the new road in Chenango County came from NY 23's former routing and NY 319 near Norwich, both of which were transferred to Chenango County after the new highway was completed. Suffixed routes NY 23A () is an alternate route of NY 23 through Greene County. The route separates from NY 23 near Prattsville, passes through the northern portion of Catskill State Park, and ends at US 9W in Catskill south of where US 9W meets NY 23. It was assigned in the mid-1920s. NY 23B () is