The New York State Department of Transportation (NYSDOT) is responsible for the establishment and classification of a state highway network which includes Interstate Highways, U.S.

The New York state highway system is supplemented by the state's county route system, which comprises a series of highways numbered and maintained by the individual county highway departments.

These county-maintained segments also carry a county route designation that may or may not be posted alongside the U.S. or state designation, depending on the signing practices of the county.

Highways maintained by the New York State Thruway Authority lack any signed numbers apart from Interstate Highway designations.

There are no standard NYSDOT reference markers on any of the highways; instead, the Thruway Authority posts their own mileposts, which (aside from the mainline) bear special Thruway codes.