In 1899, after the construction of the Panevėžys-Švenčionėliai narrow gauge railway through Saldutiškis at the initiative of Boleslovas Jaloveckis, the settlement of Saldutiškis started to grow. Then a road was built between the narrow gauge railway station and the manor, some poplars were planted.
During the German occupation of Lithuania in 1915-1918, Saldutiškis became the centre of the county (Kreis Sołdaciszki, Sylgudiszki or Saldugischki) with its headquarters at Saldutiškis Manor. The county covered a part of Švenčionys county and Zarasai county in Tsarist times, including Ignalina, Dūkštas, Salakas, Tauragnai.
Mečislovas Jaloveckis, Boleslov’s only son, worked as a clerk at Vilnius Land Bank. He travelled extensively throughout Lithuania and captured about 1500 Lithuanian and Polish manor houses in his watercolour paintings. After his father’s death, Mečislovas Jaloveckis returned to Lithuania, however, he did not stay at Saldutiškis but left for Poland, in 1962, he died in London.