After the war, the local population, largely depleted during the war, started to recuperate. A notable influx of Poles resettled from the Polish areas annexed by the Soviet Union allowed for fast reconstruction of the town. In 1956, after the administrative reform of that year, Sejny once again became a seat of a powiat. Although it was cancelled in 1975, the new administrative division of Poland passed in 1999 reinstituted it. Depopulation may ultimately again threaten the present local and regional administrative organisation.