The Riga–Daugavpils railway line (Latvian: Dzelzceļa līnija Rīga—Daugavpils) is a 218-kilometre (135 mi) long railway line in Latvia which connects the cities of Riga in central Latvia and Daugavpils in south-eastern Latvia. The railway line is double track between Riga and Krustpils and single track between Krustpils and Daugavpils. The track gauge is 1,520 mm (4 ft 11+27⁄32 in) (Russian gauge). It was built in 1861, and is one the oldest railway lines in Latvia.