Why were Treblinka, Sobibor, and Belzec closed in 1943?

The extermination camps of Treblinka, Sobibor, and Belzec were closed in 1943 because their primary objective—the systematic murder of the Jewish population within the ghettos of occupied Poland—had been largely completed.1

These sites were established as part of Operation Reinhard, a campaign specifically designed to eliminate the Jewish population of central and eastern Poland. Once the Nazis had emptied the ghettos and murdered the vast majority of their inhabitants, the camps were no longer required for their original purpose. Following the cessation of operations, the Nazis dismantled the facilities, exhumed and cremated mass graves to destroy evidence of their crimes, and planted the areas with trees to conceal the sites' functions.2314