Orsk is the second largest city in Orenburg Oblast, Russia, located on the steppe about 100 kilometers (62 mi) southeast of the southern tip of the Ural Mountains. The city straddles the Ural River. Population: 239,800 (2010 census); 250,963 (2002 census); 270,711 (1989 Soviet census). It lies adjacent to the Kazakhstan–Russia border.