The Western Balkan route has seen an unprecedented wave of migration, which peaked in the second half of 2015. In 2015 and 2016, the route experienced changes and a high degree of unpredictability due to modifications in the entry criteria. First a fast transit route, initially affording passage through Serbia to Hungary and later deviating towards Croatia and Slovenia (September 2015), it was finally closed in March 2016, leaving migrants trapped in Serbia and FYR Macedonia. New alternative routes appeared, such as the land route between Serbia and Bulgaria. Individual countries’ decisions to build fences, reinstate border checks and change policies triggered a ‘cascade effect’, which in turn sparked tensions between Serbia and Hungary, and later Serbia and Croatia, resolved relatively quickly. In early 2016, the Western Balkan route was closed to persons of other than Afghan, Syrian and Iraqi origin, as they were viewed as ‘economic migrants’. In February, Afghans too were removed from that list, leaving a growing number of them stranded along the route. In March, a 19-point plan led to new restrictions: Slovenia and Croatia started applying new Schengen zone entry rules, under which only migrants with valid passports and visas were allowed to enter. Serbia followed suit, reciprocally applying these rules on its southern and eastern borders. On 20 March, the EU-Turkey joint action plan came into effect, resulting in the official closure of the Western Balkan route. People who remained in transit sites in the region had limited legal options for moving on, which led to more migrants applying for asylum in both Serbia and FYR Macedonia, in order to extend their legal stay (beyond 72 hours) and receive shelter and assistance. Nevertheless, Serbia remained mainly a transit country where migrants spent two days on average. Although no exact data are available, Serbian NGO Grupa 484 says that over 650 000 migrants and refugees, mostly from Syria, Afghanistan and Iraq, were registered in Serbia between June 2015 and June 2016. There are no reliable estimates as to the number of unregistered asylum-seekers and migrants.