Selections of mass Jewish transports took place on three railroad unloading platforms, or ramps. SS doctors made most of the decisions about who was qualified for labor, and who was killed immediately.

The first unloading ramp , located adjacent to the main camp, was in use throughout the period when the camp was in operation and mainly served the main camp. This is where the first transport of 728 prisoners from Tarnów was unloaded on June 14, 1940. Later transports of Poles also arrived here, as did, from 1942, some mass transports of Jews. It was also at this ramp, during the years 1941-1942, before the building of the Buna sub-camp, that the prisoners constructing the Buna-Werke (the IG Farbenindustrie plant) boarded the train that carried them to labor, and disembarked on their return to the camp.

The second ramp  [the so-called “Alte Judenrampe”] went into operation in 1942. It was located on the grounds of the O?wi?cim freight station, between the Auschwitz and Birkenau camps. This is where the majority of the mass transports of Jews arrived between 1942 and May 1944, as well as the mass transports of Roma and Sinti who were imprisoned in the Birkenau camp beginning in February 1943.

At first, selections of mass Jewish transports took place sporadically. Only after July 4, 1942 did selection take place regularly. Almost all the mass transports of Jews to Auschwitz after that date were subject to selection.

The third ramp  was built from 1943 inside the Birkenau camp, and went into operation in May 1944 in connection with the anticipated arrival of transports of Hungarian Jews. The railroad spur along this ramp ran as far as gas chambers and crematoria II and III. Aside from the 430 thousand Hungarian Jews, 67 thousand Jews from the Łód? ghetto and some of the transports from the ghetto in Terezin and from Slovakia were unloaded at this ramp. From this point on, mass selections of Jews took place inside the camp, before the eyes of thousands of prisoners. Transports of Poles from Warsaw during the Uprising there, sent to Auschwitz by way of the transit camp in Pruszków, were also unloaded here.

All three ramps also served as embarkation points for prisoners transferred from Auschwitz to sub-camps and other concentration camps.

The selection procedure carried out on the ramps was as follows: families were divided after leaving the train cars and all the people were lined up in two columns. The men and older boys were in one column, and the women and children of both sexes in the other. Next, the people were led to the camp doctors and other camp functionaries conducting selection. They judged the people standing before them on sight and, sometimes eliciting a brief declaration as to their age and occupation, decided whether they would live or die. 

Age was one of the principal criteria for selection. As a rule, all children below 16 years of age (from 1944, below 14) and the elderly were sent to die. As a statistical average, about 20% of the people in transports were chosen for labor. They were led into the camp, registered as prisoners, and assigned the next numbers in the various series. Of the approximately 1.1 million Jews deported to Auschwitz, about 200 thousand were chosen in this way. The remainder, about 900 thousand people, were killed in the gas chambers.