While driving along any state route in New York State, one will see small green
signs such as the one shown above at the side of the road. These signs are
called reference markers and denote your exact location in the state route system.
They are located on all state routes, except roads maintained by the New York
State Thruway Authority and sections of state routes that are locally maintained
by a county, town, or city. There are also no reference markers on state routes
within the City of New York that are not limited access. The signs have three
lines of numbers and can be decoded as follows:
The first line of a reference marker contains the route number of the road that
you are travelling on. If the road is an interstate highway, the number will be
followed by the letter "I". Parkways and other state routes that do not have
posted route numbers are assigned numbers called reference routes that appear in
the first line of reference markers. A list of reference routes in the New York
metropolitan area is available in the route listings section. Although service
roads are assigned reference routes, the number of the main highway appears on
the first line of the reference markers of service roads.
The second number is somewhat more complicated. The first digit identifies the
region of the state that you are in. The region code for New York City is X and
the region code for Long Island proper (Nassau and Suffolk counties) is 0.
Westchester and Rockland counties are in Region 8. The second digit is the
county code. The last two digits of the second line are the county order number.
This will be 01 for the first county that the road passes through, 02 for the
The third number is the mileage counter. Within each county, each state route is
divided into one or more sections called control segments. The first digit of
the third number is the number of the control segment. The last three digits are
the distance in tenths of miles from the beginning of the control segment to the
reference marker. The mileage counter always counts from south to north or from
west to east, regardless of the direction in which the exit numbers increase.