NM 502 eastbound just east of the junction with NM 30
The route is paved for its entire length, in contrast to some other state highways in northern New Mexico. NM 502 begins at its western terminus at NM 501 and heads due east through Los Alamos as Trinity Drive. It also begins as a four-lane road heading through town. As it exits town, it narrows down to two lanes and it then passes by the Los Alamos Airport, running parallel with its runway. It then reaches a junction with NM 4 at an interchange before continuing east with five lanes through the spectacular canyon/mesa country of the Pajarito Plateau. The highway then reaches another junction with NM 30 that goes north to Santa Clara Pueblo and Española. The route becomes a four-lane road and then crosses over the Rio Grande beside the historic Otowi Bridge. The route then passes south of San Ildefonso Pueblo and through El Rancho before reaching its eastern terminus at a single-point urban interchange (SPUI) at U.S. Route 84 (US 84) and US 285 in Pojoaque. The total length is about 18 miles (29 km). NM 502 was formally continuous with NM 501, which continues east from another junction with NM 4 to Los Alamos in the foothills of the Jemez Mountains. NM 502 has been a designated "safety corridor" for most of its length since November 2005, with speed limits restricted to 55 miles per hour (89 km/h) maximum, and lower through the towns and on the steep curves near the intersection with NM 4. Prior to 2007, the speed limit along the stretch from San Ildefonso Pueblo and Pojoaque Valley High School was 65 mph.
Despite Pojoaque being the eastern terminus, Santa Fe is the eastbound control city on NM 502 since traffic typically continues onto US 84 / 285, which does reach Santa Fe.
