County Route 18 (Columbia County, New York)

County routes in Columbia County, New York, are signed with the Manual on Uniform Traffic Control Devices-standard yellow-on-blue pentagon route marker. All roads maintained by Columbia County are assigned a county highway number; this number is unsigned. Each county route comprises one or more county highways; however, not all county highways are part of a signed county route.

Every county-maintained road is assigned an unsigned county highway number for inventory purposes. The majority of county highways are part of signed county routes; however, some are not posted with any designation. Those highways or parts of highways that are not part of any county routes are listed below.

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