European leaders will meet next week to discuss the migration crisis and border control proposals, as members of the European Union are increasingly divided over the future of the bloc’s free movement area, Schengen. The Schengen agreement removed border controls of 26 European countries and allowed people to move from one country to another without needing to receive visas or stop for border checks once inside the zone. There are growing indications that the free movement agreement is under threat. Over the past few weeks, Greece has been threatened with suspension from the Schengen zone, and Germany and France floated a plan to allow for a European border control force to be deployed, if necessary, regardless of whether or not the host country approved. As well, the Dutch raised the idea of a mini-Schengen zone and Central European leaders publicly expressed fears of exclusion from the free movement zone.

Following the intensification of the refugee crisis in the summer and fall months, as well as the Nov. 13 terror attacks in Paris, more Schengen countries have implemented at least temporary, ad hoc border checks within the free movement area. Countries that have implemented at least partial border checks include France, Germany, Sweden, Norway, the Netherlands, Austria, Slovenia, and Slovakia. At the same time, fences or partial fencing has been set up along the Hungarian-Croatian, Hungarian-Serbian, Austrian-Slovenian, Slovenian-Croatian, and Macedonian-Greek borders. In effect, about a third of Schengen members have implemented either new border checks or new border infrastructure over the past three months. Temporary border controls across the continent are undermining the Schengen agreement, and there are more and more indications that the Schengen zone will not survive in a fragmented Europe, at least not in its current form.

Imagining a Europe without Schengen is difficult because the return of border controls means much more than an extra passport stamp each time a person crosses from one European country to the next. It is estimated there are 1.25 billion border crossings within the Schengen zone each year, though the exact figure is impossible to know. But along with people, there are also goods crossing Europe’s still largely invisible borders. Some of these goods are headed to neighboring countries, or passing through them en route to other states, while some are destined for markets as far as China and the U.S.

The absence of border controls greatly facilitates both intra-European and external trade flows. In trade, it is not enough to export products with high demand – it is highly important to be able to transport goods rapidly and efficiently to their destinations. In the European Union, the largest exporters to other European countries are Germany and the Netherlands. Germany is Europe’s industrial powerhouse. Germany and the Netherlands also are home to Europe’s two busiest ports, the Port of Rotterdam and the Port of Hamburg. But besides industrial production and geographic proximity to maritime routes, a part of what makes these two countries so competitive is the quality of their transport logistics. Each year, the World Bank produces a global report called the Logistics Performance Index. The Index uses factors such as timeliness, ease of arranging shipments, and quality of infrastructure to rank countries’ logistics capabilities. In 2014, Germany was ranked number one internationally in terms of logistics performance, followed by the Netherlands in second place.

The reintroduction of border controls across Europe would undermine the ability of countries to transport goods rapidly. In 2014, Germany had the third-most freight for transport in the EU, behind Spain and Poland. Within Schengen, the top destinations for German exports, by value, are France, the Netherlands, Austria and Italy. In fact, according to the European Commission, one of the busiest freight routes in Europe is the Rhine-Alpine Corridor, which connects the North Sea ports in Germany and the Netherlands with Italy and the Mediterranean basin in the south. Should Schengen no longer exist and border controls spring up across the entire zone, a truck travelling from the Port of Rotterdam to Italy might have to stop for border checks at least three times. Depending on the amount of resources each country would devote to efficient controls, these controls could create a series of bottlenecks for trade flows throughout the continents, increasing costs and reducing competitiveness.

Besides creating delays and imposing financial costs, border controls across Europe would also change trade patterns and impact local economies. When Schengen was expanded to include the European Union’s eastern members, such as Poland and Hungary, these countries became more attractive as transport routes for both north-south and east-west trade. In terms of tonnage, the number one destination for German road freight is Poland. Poland joined Schengen in late 2007. Between 2006 and 2012, total freight transport in Poland more than doubled. Poland’s central geography and accession to Schengen has allowed the country to develop a large-scale logistics industry, providing storage facilities and other services. Smaller Central European countries have come to play a similar role. In fact, more exports are moved through Poland, Slovakia and Hungary en route to destination countries than any other EU states.

The tourism industry will likely suffer as well. A foreign tourist hoping to take a trip to Italy, France, and Spain may in theory have to apply for three separate visas, a cumbersome prospect. Millions of foreign travellers apply for Schengen visas each year. Passenger trains would see longer trip times, as border authorities would board every train to check passports. Governments will have to invest in new border infrastructure and technology, from fences and cameras to processing systems at border checkpoints. New staff will have to be hired and trained, both for conducting checks and providing security along borders.

We are not arguing that Schengen is dead. In fact, the high cost of reverting to border controls signals that many governments have a strong interest in its continued existence. Nevertheless, as the European Union becomes more fragmented and European governments increasingly unable to make cohesive decisions, states will find themselves making often times suboptimal decisions. More border controls will likely come into effect throughout the Schengen zone. As leaders remain divided over how to address Europe’s crises — especially when it comes to external borders — prospects for Schengen’s survival grow dim.