About NYS Reference Routes
The NYS Department of Transportation assigns numbers in the 900 series to all state roads not signed as touring routes. This includes NYSDOT-maintained highways as well as the NYS Thruway system and all parkways (NYSDOT or otherwise). Reference routes may be short legs connecting one touring route to another, stubs of former touring routes that are still state maintained (these usually end at city lines), or short extensions of touring routes where state maintenance extends beyond one touring route that is the terminus of another. They may also be substantial highways themselves, such as SR 952Q (Walden Avenue) east of Buffalo, which for much of its length is a 4- to 6-lane divided thoroughfare. They range in length from 0.03 miles (a few examples exist) to 104.12 miles (SR 987G, the Taconic State Parkway). The longest non-parkway reference route is the above-mentioned SR 952Q at 14.08 miles.
All reference routes are given a 3-digit + letter designation. The first digit is always 9. The second indicates the NYSDOT Region number. For this purpose, Regions 10 and 11 (which at one time were a single Region 10) use the numeral zero. Two exceptions exist: SR 907K (Cross County Parkway) and SR 907W (Hutchinson River Parkway), both of which lie in Westchester County, in Region 8.
The third digit indicates the type of road. Numbers 0-5 indicate general highways, number 6 is used for service roads, and numbers 7-9 are used for parkways. The letter is used as an additional sequential indicator. The following letters are not used:
I - used for Interstates
In addition, the letters Q and U are no longer being assigned, although examples of both exist today. (The letter U is used in NYSDOT records to distinguish US 2 and US 15 from NY 2 and NY 15.)
As with all route numbers, the reference route number can be found as the top line on NYSDOT reference markers; however, this is not always the case. Just as touring routes' reference markers may bear a former route number (due to a decommissioning or realignment), so may reference routes' markers. Also, older reference routes used a different system: they had simple 3-digit numbers in the 800 and 900 series, which are often retained on reference markers.