In South America, Argentina and Chile use track gauge, as well as or metre gauge.
Brazil uses (known as "Irish gauge", most common for passenger services and a few corridors in the Southeast) and (known as "narrow gauge" or "metre gauge", most common for cargo services). Exceptions are the Estrada de Ferro do Amapá north of the Amazon River, which has gauge, and the Lines 4 and 5 of São Paulo Metro, which also use standard gauge.
Argentina (partly), Venezuela, 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), slightly more than 60 km, uses standard gauge. The El Cerrejón Coal Railway in Colombia is also .
There are and were also some lines using different narrow gauges; see Narrow-gauge railways in South America.