The highway system of Niagara County, New York, comprises 1,673.2 miles (2,692.8 km) of roads maintained by the New York State Department of Transportation, the county, and its towns and villages. 31 state-maintained highways enter the county, which account for a combined 267.0 miles (429.7 km) of the state highway mileage in New York. 21 of the highways are signed state routes; the other 10 are unsigned reference routes. The state roads are supplemented by 283.2 miles (455.8 km) of county-maintained highways, which carry unsigned county route designations. Niagara County is also served by three byways—the Seaway Trail, the Niagara Historic Trail, and the Niagara Wine Trail.