Šalčius was born in the Čiudiškiai village in the modern Prienai district, central Lithuania (at that time part of the Russian Empire).

After Lithuania gained independence in 1918, Šalčius returned there and worked as a journalist (he was the director of the ELTA news agency).

In 1929, Šalčius, together with another famous Lithuanian traveler, Antanas Poška, began a great journey through the Balkans, Greece, Egypt, Near East to India.

Šalčius planned to journey through all the Americas to Alaska, but he became sick with malaria and encephalitis and died in the town of Guayaramerín, Bolivia.

In 2005, an expedition organized by Lithuanian travelers and journalists reached Guayaramerín and marked the approximate location of Šalčius' burial with a bas-relief.