This is a category for all railways of Russian gauge (1,520 mm or 1,524 mm) gauge in the former Soviet Union and neighbouring countries like Finland and Mongolia.

Originally, Russian gauge was 5 ft (1,524 mm). In the 1960s, the track gauge in the former Soviet Union was defined at 1,520 mm (4 ft 11+27⁄32 in).

• Category:5 ft gauge railways are or were found in Afghanistan, Finland, Sweden (Only at the Finnish border), United States until 1886 in the South, Panama until 2000 and the former Soviet Union

• Category:1520 mm gauge railways are (partially) in Armenia, Azerbaijan, Belarus, Bulgaria, Estonia, Georgia, Germany, Hong Kong, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Mongolia, North Korea, Poland, Russia, Slovakia, Tajikistan, Turkmenistan, Ukraine and Uzbekistan