county, south-central New York state, U.S., bounded by the Unadilla River to the east. It consists of a hilly region drained principally by the Chenango River (which bisects the county north-southwest) and by the Otselic, Susquehanna (Susquehanna River), and Sangerfield rivers. Parklands include Bowman Lake and Hunts Pond state parks. Hardwoods are abundant in forested areas.

Iroquoian-speaking Indians resided in the area until the late 18th century. The county was formed in 1798, its name derived from an Onondaga word meaning “thistle.” In addition to Norwich, the county seat, the principal communities are Greene, Oxford, Bainbridge, and Sherburne.

County residents engage in agriculture and manufacturing. Area 895 square miles (2,317 square km). Pop. (2000) 51,401; (2007 est.) 51,207.