The Abra del Acay in La Poma Departament, Salta Province, Argentina may be the highest point along a National Route anywhere in the world. Located at , its altitude is 5,061 meters (16,604 ft),[1] even though an old sign informs visitors it stands at 4,895 meters (16,060 ft).
The Abra del Acay is approximately 25 kilometers (16 mi) geodesic distance southeast from San Antonio de los Cobres, although the direct route by road is about 45 kilometers (28 mi).
Inaugurated on 8 July 1960 after three years of construction, this unpaved part of the National Route 40 is only suitable for all terrain vehicles, with the exception of some months in the year when meteorological and maintenance conditions allow normal vehicles to transit. The road inclination of 4.5 % and the oxygen reduction due to altitude make the crossing difficult for both vehicles and humans.