New Mexico State Road 556 (NM 556) is a 15.402-mile-long (24.787 km) state highway entirely within Bernalillo County, New Mexico. For most of its length, NM 556 is signed as Tramway Boulevard in Albuquerque, although from I-25 to its northern terminus at NM 47, NM 556 is signed as Roy Road. The highway's southern terminus is at an intersection with NM 333 and Historic U.S. Route 66 (Historic US 66), or Central Avenue. The highway then moves north intersecting with Interstate 40 (I-40). The highway is a divided four-lane road until its intersection with Tramway Road. After that, the highway narrows to two lanes and takes a westerly turn to intersect with I-25. The highway's northern terminus is at an intersection with NM 47.
^"NMDOT State Routes"(PDF). New Mexico Department of Transportation. Retrieved 2008-05-15.