Doctor Arroyo (ah-RO-yo), city (1990 pop. 6,025) and township, S Nuevo León, N Mexico, on the Mesa Central, 30 mi/48 km E of Matehuala (San Luis Potosí); 23°40'N 100°10'W. Elev. 5,794 ft/1,766 m. Ranching, grazing, farming area. Small industry in city.