More intensive development of railways in Latvia commenced the following year, 1861, when the 232 km long Riga - Dinaburg railway was opened. It connected with the Saint Petersburg – Warsaw Railway, and thus joined the Latvian railways with the Russian rail network. For the rest of the second half of the nineteenth century, the intensive construction of railways continued. Lines constructed during that period included Dinaburg–Radviliškis, Mitau (now Jelgava)–Muravyovo (Mažeikiai), and others.
From the 1890s, narrow gauge lines (750 mm (2 ft 51⁄2 in)) were built to complement the broad gauge lines (1,524 mm (5 ft)). Most of the narrow-gauge railways were later converted to broad gauge, but then dismantled in the second half of the twentieth century.