High Quality Content by WIKIPEDIA articles! There are currently 31 Interstate Highways—8 main routes and 23 auxiliary routes—that exist entirely or partially in the U.S. state of New York. In New York, Interstate Highways are mostly maintained by the New York State Department of Transportation (NYSDOT), with some exceptions. Unlike in some other states, Interstate Highways in New York are not directly referenced by NYSDOT with their number; instead, the letter "I" is suffixed to the number of the route on reference markers and in internal documents. On the surface, there appears to be numerical duplication between Interstate Highways and state routes—such as I-86 (I-86) and NY 86—but the "I" suffix that is appended to Interstate Highway numbers allows the Interstate Highway and state route to co-exist ("86I" versus "86", respectively).