Classically, the border of the modern nation-state marked the locus of legitimate control of access to its territory. Since every border-crosser was checked there for valid travel documents, the border served as a physical barrier to all types of mobility (Torpey 1998; Zolberg 2006). Today, we can observe that human mobility is increasingly regulated well in advance, that is, before arrival at the border. More than ever, people are scrutinized by or on behalf of the destination country far away from that country’s territory. Well in advance of departure, many travelers have to apply for permission to enter via embassies and consulates. By the same token, advance controls by airline liaison officers and private transport companies target those without valid travel documents. Through the creation of “buffer zones”, countries of origin and transit countries also engage in mobility control (Wallace 1995). These means are intended to keep unwanted travelers from continuing or even starting their journey. If these control instruments fail to fulfill their purpose, people seeking to cross a border illegally are stopped right in front of the border. Step by step, border control agencies proceed to sort out those who are not welcome. Thus, border control is designed like a “filter system” with a layered, gradated series of access control mechanisms.1