County Route 18 (CR 18) is a county-maintained highway in western Otsego County, New York, in the United States. It extends for 34.83 miles (56.05 km) from an intersection with New York State Route 51 (NY 51) in the town of Butternuts to the Oneida County line at Plainfield, where it becomes CR 2. The highway runs along the eastern bank of the Unadilla River and parallels NY 8, which follows the western bank of the river. CR 18 enters the vicinity of several villages and hamlets, including the village of New Berlin and the hamlet of Unadilla Forks.