The state roads are supplemented by 257.9 miles (415.0 km) of county-maintained highways, which carry unsigned county route designations.

It is named Main Street when it enters the county and intersects NY 77 in Pembroke.

Almost immediately after the county line, Route 19 stops at a traffic light with NY 63 in the hamlet of Pavilion.

The similarly named but smaller Pavilion Center marks the junction with US 20, 2.3 miles thereafter.

Shortly afterwards, it crosses the I-90 segment of the New York State Thruway just west of the I-490 exit.

Several miles later, after passing the Bergen Swamp Wildlife Refuge, it crosses the Monroe County line.

It passes Genesee Community College, then, continuing its northward slant, crosses under I-90 (the Thruway) with no exit.

Less than a quarter of a mile from its western terminus, Route 33A connects to I-490 at exit 2, located on the Genesee–Monroe county line.

After the traffic light at the center of the hamlet, NY 63 crosses Oatka Creek and climbs back up out of the Wyoming Valley.

It continues northwestward as Lewiston Road to the village of Oakfield, where NY 262 has its western terminus.

North of the falls, the land once again becomes mostly fields, although some are marked with signage for the nearby Iroquois National Wildlife Refuge.

The Alexander Road name remains through Alexander, past CSX Transportation's Rochester Subdivision rail line in the town of Batavia (which NY 98 passes under), and up to the Batavia city limits, where it becomes Walnut Street.

The two routes join on Oak Street for one block to cross over Tonawanda Creek.

Route 237 continues north through the hamlet of Pumpkin Hill before crossing into Orleans County.

NY 238 continues on a northwest path into the town of Alexander from the Orleans County village of Attica.

It closely follows Norfolk Southern Railway's Buffalo Line through this area, and is mirrored by CR 45 on the opposite side of the tracks, which terminates at NY 238 at both ends.

After CR 45's western terminus, NY 238 turns more northward again, entering a residential area and terminating at US 20 in Darien.

Its current routing between Depew and Avon became part of NY 35, which also served downtown Buffalo.

[4] US 20 was rerouted to follow its current alignment between Hamburg and Avon in the late 1930s, replacing NY 35.

County routes generally comprise one or more named roads strung together to form a single continuous unit.