Track gauge in South America

Argentina and Chile use 1,676 mm (5 ft 6 in) "Indian gauge" as well as 1,000 mm (3 ft 3 ³⁄₈ in).

Brazil uses 1,600 mm (5 ft 3 in) (known as "Irish gauge", most common for passenger services and a few corridors in the Southeast) and 1,000 mm (3 ft 3 ³⁄₈ in) (known as "narrow gauge" or "metre gauge", most common for cargo services). Exceptions are the Estrada de Ferro do Amapá North of the River Amazon, which has 1,435 mm (4 ft 8 ¹⁄₂ in) gauge and the new Line 5 of São Paulo Metro, which also uses standard gauge.

Argentina (partly), Paraguay, Uruguay and Peru use standard gauge. In the past a few lines in Northern Chile also had standard gauge, as the only international railway between Arica (Chile) and Tacna (Peru) a bit more than 60 km has standard gauge. The El Cerrejón Coal Railway in Colombia and the Venezuelan Railways are also 1,435 mm (4 ft 8 ¹⁄₂ in).

There are and were also some lines using different narrow gauges, see the "narrow gauge" section in List_of_rail_gauges#Uncommon_or_obsolete_gauges