Borders in Flux: Migration, Nationhood, and the Making of Modern Europe

• Introduction
• Chapter 1 Concepts of Borders, Mobility, and Nationhood
• Chapter 2 Mapping Movement in the Long Eighteenth Century
• Chapter 3 Revolution, War, and the Passport: 1789–1815
• Chapter 4 Empires in Motion: Habsburg, Ottoman, and Russian Circulations
• Chapter 5 Industrialization, Urban Growth, and Internal Migration
• Chapter 6 1848 and the Making of National Citizens
• Chapter 7 Unification and Exclusion: Germany and Italy, 1860–1914
• Chapter 8 Overseas Emigration: Europe to the Americas
• Chapter 9 Minorities on the Margin: Jews, Roma, and Statelessness before 1914
• Chapter 10 Total War and the Refugee: 1914–1923
• Chapter 11 Redrawing the Map: Treaties, Population Exchanges, and New Borders
• Chapter 12 Paper Citizens: Passports, Visas, and the Interwar State
• Chapter 13 Dictatorship, Persecution, and Flight in the 1930s
• Chapter 14 World War II: Deportation, Genocide, and Displacement
• Chapter 15 Aftermath and Return: DPs, Expulsions, and Reconstruction
• Chapter 16 Crossing the Curtain: Mobility in Cold War Europe
• Chapter 17 Decolonization Comes Home: Postcolonial Migration to Europe
• Chapter 18 Workers in Motion: Guestworker Systems, 1950s–1970s
• Chapter 19 Europe without Internal Frontiers? Schengen, Dublin, and the EU Border Regime
• Chapter 20 1989 and After: Borders, Breakups, and the Balkans
• Chapter 21 Islam, Integration, and the Politics of Belonging
• Chapter 22 Technologies of Control: Databases, Fences, and the Mediterranean
• Chapter 23 The 2015–2016 Refugee Arrivals in Context
• Chapter 24 Populism, Brexit, and the Return of the Nation
• Chapter 25 War and Displacement in Ukraine and Beyond

Borders in Europe have never been still. They bend to the pressures of war and diplomacy, harden under the weight of fear, and relax when commerce or political imagination demands it. This book argues that the most powerful force shaping those lines has been the movement of people—migrants, refugees, expellees, itinerant workers, and students—whose trajectories compelled states to define who belonged, who did not, and on what terms. By placing mobility at the center of Europe’s modern history, Borders in Flux shows how population movement forged national identities, reconfigured citizenship, and seeded both solidarities and conflicts that echo into the present.

Our approach blends demographic analysis with personal narratives. Numbers reveal patterns—surges and lulls, corridors and chokepoints, age and skill profiles—that link economic cycles, wars, and policy regimes to measurable shifts in mobility. Yet statistics alone cannot explain why people set out, how they endured the journey, or what it felt like to arrive and be classified by a border guard, a mayor’s office, or a neighborhood committee. Diaries, letters, oral histories, and case files restore the textures of experience: the forged pass folded into a boot, the reunion at a train station, the silence after a denial. Together, these methods illuminate how policies were lived and how, in turn, lived realities reshaped policy.

Chronologically, the book spans from the eighteenth century to the present, a period in which European states experimented with passports, censuses, and conscription; consolidated and collapsed empires; fought total wars; dismantled colonial rule; built welfare states; and, most recently, pooled sovereignty in the European Union while fortifying external frontiers. Each transformation changed who counted as a national subject and how borders operated in practice. The longue durée perspective allows us to track recurring dilemmas—security versus liberty, labor demand versus social protection, humanitarian norms versus political backlash—and to see how today’s debates reprise older scripts even as technologies and geopolitical contexts evolve.

Thematically, we examine three entwined processes. First, nation-making: how elites and movements defined “the people,” often through inclusionary promises to some groups and exclusionary measures against others. Second, state capacity: how institutions—from municipal registries to continental databases—rendered populations legible and governable, turning mobility into a site of administrative innovation. Third, contention: how migrants and their advocates, as well as nativist actors, mobilized to contest policies on the street, at the ballot box, and in the courts, thereby redirecting the arc of border politics. These processes never move in perfect synchrony; their frictions are where much of modern Europe was made.

While historical in orientation, the book is policy-relevant. It offers context for interpreting contemporary controversies over asylum, irregular entry, labor recruitment, and integration by showing their historical roots and unintended consequences. Episodes such as the post–World War II expulsions, the guestworker programs of the 1950s–1970s, the removal of many internal border controls under Schengen, and recent surges in protection claims are not isolated anomalies; they are chapters in a longer struggle to align sovereignty, mobility, and rights. Understanding what worked, what failed, and why can help policymakers and citizens weigh trade-offs with clearer eyes.

Finally, a note on perspective. Borders are institutions, but they are also workplaces for officials and thresholds for travelers. They exist on maps and in memory. By following both the macro-curves of population movement and the micro-stories of border encounters, we aim to bridge scales and disciplines. The result is neither a celebratory narrative of openness nor a lament of inevitable closure. It is a history of experimentation and contestation—of how Europeans have repeatedly redrawn the line between “us” and “them,” and of how people in motion have continually shown that the line is, in practice, a zone of negotiation.

The chapters that follow move between continental panoramas and grounded case studies to show how migration has made and remade Europe. Readers will encounter shipping lanes and train timetables, passport rules and amnesty decrees, censuses and strike votes, detention sites and family kitchens. Across these settings, one theme persists: borders change when people move, and when people move, borders change them in return.

A border can be many things at once: a line scratched on a map, a fence studded with floodlights, a sheaf of stamps in a passport, a feeling that washes over you when someone asks where you are from. It can be a razor-wire barrier in the mountains or an unmarked meadow where one country simply stops and another begins. Borders exist in the material world and in the imagination, and one of the central arguments of this book is that the two are never quite separable. To understand how Europe's borders have been drawn, erased, and redrawn over the past three centuries, we first need to get a handle on what borders actually are, how they relate to movement, and why they have so often become entangled with the even slipperier idea of the nation.

The word "border" comes from the Old French bordure, meaning an edge or a trimming, something that marks where one piece of fabric ends and another begins. For most of European history, that is about how people experienced boundaries too: as rough edges, zones of overlap, places where allegiance, language, and custom bled into one another. The tidy lines we see on modern maps are a relatively recent invention, and their neatness is largely an illusion. A straight border on a cartographer's sheet corresponds, on the ground, to a river that floods and shifts its course, a mountain ridge whose peak is disputed by shepherds on both sides, or a village whose inhabitants speak two languages and pay taxes to two lords. The map says there is a line. The reality says otherwise.

Lines, Zones, and Thresholds

One useful way to think about borders is to distinguish between three layers that almost always coexist but rarely coincide perfectly. The first is the geopolitical border: the line that appears on official maps, defined by treaty or conquest, and recognized—if not always respected—by neighboring states. The second is the administrative border, the set of legal instruments, checkpoints, registries, and bureaucratic procedures through which a state tries to make that geopolitical line real and enforceable. The third is the symbolic or cultural border: the mental map that people carry in their heads, marking who belongs and who does not, where "home" ends and "elsewhere" begins. These three layers can be in harmony during periods of political stability and shared identity, but more often they pull against one another. A person may live on the "right" side of the geopolitical border but be regarded, by neighbors and officials alike, as belonging to the other nation. Or a state may claim sovereignty over territory it cannot effectively administer, leaving a gap between the map and the ground that migrants, smugglers, and refugees have always been adept at exploiting.

The historian Alfred Cobban once remarked that before the nineteenth century, most European borders were "lines on a map which diplomats were fond of drawing but which bore little relation to conditions on the spot." He was exaggerating, as anyone who has tried to smuggle contraband across any border in any century would testify, but the kernel of truth is important. For much of the early modern period, sovereignty was layered and overlapping. A peasant in the Pyrenees might owe feudal obligations to a lord on one side of the watershed and spiritual allegiance to a bishop on the other. A merchant in the Low Countries could pass through dozens of toll gates in the course of a single day, each one a minor border of sorts, each demanding a fee and a scrap of paper. The idea that a state's authority should be absolute within a defined territory—that is, the modern concept of territorial sovereignty—was an aspiration long before it was a fact.

This matters because the very notion of crossing a border illegally presupposes that the border is clear, firm, and legitimate in the eyes of those who enforce it and those who live near it. In the eighteenth century and earlier, the question of whether a particular stretch of land belonged to one polity or another was often genuinely open. People moved across regions, following harvests, wars, trade routes, or family networks, with far less concern for political frontiers than we might assume. That is not to say mobility was unregulated. Tolls, transit permits, vagrancy laws, and guild restrictions all shaped who could move, where, and under what conditions. But the regulatory logic was different from what came later, focused less on national identity and more on economic interest, public order, and dynastic loyalty.

Mobility as a Given

Human beings are, by nature and by necessity, a mobile species. The history of Homo sapiens is, at its most fundamental level, a history of movement: across savannas, along coastlines, over mountain passes, and eventually across oceans. In Europe, patterns of migration have been shaped by geography—the great river systems, the mountain chains, the proximity of the Mediterranean and the North Sea—as much as by politics. The Rhine and Danube corridors, the passes through the Alps and the Pyrenees, the coastal routes linking Iberia to North Africa and Scandinavia to the Baltic, all predate any state by millennia and have remained arteries of movement regardless of who controls them.

Yet if mobility is a constant, the terms on which it takes place vary enormously. The medieval pilgrim setting out for Santiago de Compostela traveled under the protection of a recognized status—Christian, penitent, armed with a letter of safe conduct from a bishop or king. The vagrant who set out for no discernible purpose was a different matter, liable to be whipped, branded, or pressed into military service. Early modern European states inherited a deep suspicion of unregulated movement from the medieval and Roman traditions, in which vagrancy was closely linked to criminality, heresy, and disease. The Statute of Laborers in fourteenth-century England, which tried to freeze peasants in place after the Black Death had wiped out a third of the population, is one of the earliest and most dramatic examples of a state attempting to control mobility by law. Similar measures appeared across the continent, often in moments of labor shortage or social upheaval when the movement of people was read as a threat to the established order.

From these beginnings, the control of movement became one of the essential functions of the emerging state. It was connected to taxation—how can you tax people if you do not know where they are or when they leave?—to conscription—the military needs bodies, and those bodies must not flee—and to the maintenance of public order. The passport, which in its earliest form was a letter requesting safe passage from one sovereign to another, gradually evolved into a document issued by a traveler's own government, certifying identity and, increasingly, nationality. By the eighteenth century, most European states had some system of travel documents for their subjects, though enforcement was sporadic and the documents themselves easily forged or doctored.

The point is that borders are not simply geographic features; they are technologies of governance, tools that states build and maintain in order to manage populations. And like all technologies, they evolve in response to pressures—economic crises, wars, revolutions, demographic shifts—that no single government can fully control. A border that has worked for decades may suddenly become obsolete when a new corridor of migration opens up, or morally intolerable when a war produces millions of displaced people overnight. Understanding those pressures, and the ways states have responded to them, is what this book is about.

The Idea of the Nation

If borders are the fences, the nation is the yard—or at least, the story we tell about the yard. Nationhood, as a political concept and a lived experience, is historically entangled with borders in ways that are neither simple nor inevitable. The word "nation" derives from the Latin natio, meaning "birth" or "race," and in its earliest European usage it referred to a group of people connected by common origin, language, or kinship. In medieval universities, students from the same region were grouped into "nations" for administrative purposes—there was a French nation, a German nation, a Picard nation at the University of Paris—without any implication of statehood or territorial sovereignty. The concept was social and cultural before it was political.

The political transformation of the idea of the nation was one of the great convulsions of the late eighteenth and early nineteenth centuries. The French Revolution of 1789 did not invent nationalism, but it gave it a new vocabulary and a new institutional scaffolding. When the revolutionaries declared that sovereignty resided in the nation—the collective body of French citizens—rather than in the person of the king, they were doing something unprecedented. They were claiming that the political community was defined not by dynastic inheritance or divine right but by the will and identity of the people themselves. And who were the people? That question, once posed, could not be left unanswered. Boundaries had to be drawn, literally and figuratively, around the community of citizens. Some people belonged; others did not. The criteria for belonging—language, culture, descent, loyalty, property, residence—became the subject of passionate debate and, not infrequently, violence.

This is the moment when borders began to harden in a new way. A wall or a checkpoint is an old technology, but the idea that a border should separate distinct peoples, each governing itself in its own territory, was a genuinely modern innovation. It implied that the right to move freely across a given stretch of land was not universal but contingent on membership in the national community. It turned the stranger into a potential threat and the migrant into a problem to be solved. And it gave states a powerful new justification for controlling movement: not merely to collect tolls or prevent vagrancy, but to protect the integrity of the nation itself.

Intersections: Borders, Mobility, and Belonging

The three concepts in this chapter's title—borders, mobility, and nationhood—are not independent variables. They form a triangular relationship in which each element shapes and is shaped by the others. When a state redraws its borders, it changes the legal status of everyone who lives on the new periphery, turning neighbors into foreigners overnight and turning foreign subjects into citizens. When a wave of migration disrupts the demographic balance of a region, it can provoke a backlash in which the host community tightens its definitions of belonging, erecting new legal barriers and demanding cultural assimilation. And when the idea of the nation is itself contested—when linguistic minorities demand recognition, when religious communities refuse to assimilate, when colonial subjects claim the rights of citizenship—borders become sites of struggle rather than mere lines on a map.

Consider, by way of a brief illustration, the experience of a family living in the town of Teschen (now Cieszyn in Poland and Český Těšín in the Czech Republic) at the end of the First World War. For centuries, Teschen had been a prosperous, polyglot trading town on the border between Austrian Silesia and the Kingdom of Hungary. Its population was a mosaic of Poles, Czechs, Germans, and Jews, many of whom spoke two or three languages and intermarried across confessional lines. When the Habsburg Empire collapsed in 1918, the town was claimed simultaneously by the new Polish and Czechoslovak states. An Allied commission eventually divided it along the river Olza, splitting the town in two and, in the process, cutting through the lives of families, businesses, and institutions that had operated comfortably across the old imperial boundaries. Overnight, people who had thought of themselves as Tescheners, or as subjects of the emperor, or simply as neighbors, found themselves reclassified as Poles or Czechs, citizens of one state or the other, separated by a new border that ran through the middle of a bridge, a churchyard, a waterworks.

The Teschen case is interesting not only for what it tells us about the arbitrariness of borders but also for what it reveals about the relationship between mobility and identity. Before the partition, movement in Teschen was shaped by commerce, family, and custom, not by passports or nationality laws. After the partition, every crossing became an administrative event, subject to regulation, documentation, and surveillance. The border did not create the differences between Poles and Czechs—those existed before—but it reified them, turning a fluid cultural landscape into a set of hard categories that people were expected to fit into. That reification, and the tensions it produced, would persist for decades.

The Instruments of Control

States have never relied on fences alone to manage their borders. The history of border control is also a history of paperwork: passports, visas, entry permits, residency cards, internal travel documents, certificates of registration, identity cards, expulsion orders, and a host of other written instruments that classify and regulate human movement. The invention and proliferation of these documents is one of the great administrative stories of modern Europe, and we will follow it through the chapters that follow. For now, it is enough to note that paperwork and physical barriers are two sides of the same coin. A passport is a portable border; a checkpoint is a passport in material form.

The effectiveness of these instruments has always depended on the capacity of the state to collect, store, and retrieve information about its population. In the eighteenth century, that capacity was limited. Most European states lacked reliable census data, let alone the bureaucratic machinery to monitor individual movements. The Austrian Empire maintained one of the most sophisticated registration systems in Europe—the so-called Kontrollzone, a strip of territory along the Ottoman border where inhabitants were subject to enhanced surveillance—but even this system was riddled with gaps and corruption. People falsified documents, bribed officials, crossed at unguarded points, and simply ignored regulations when enforcement was weak. The gap between the paper border and the lived border was wide, and it remained wide well into the twentieth century.

Modern information technology has transformed that gap without closing it entirely. Electronic databases, biometric passports, facial recognition systems, and the vast data-sharing networks of the European Union have given states an unprecedented ability to track and identify individuals across borders. Schengen, the agreement that eliminated most internal border controls among its signatories, is sometimes imagined as the triumph of open borders. In reality, it shifted the locus of control from the internal frontier to the external one, relying on sophisticated databases and reinforced coast guard operations to monitor who enters the Schengen area in the first place. The border did not disappear; it moved. Understanding how and why it moved is one of the tasks of this book.

Mobility, Inequality, and the Border as Filter

Borders do not filter all people in the same way. A wealthy businessman with a biometric passport and a pre-approved visa can cross from Paris to Frankfurt with barely a glance from a customs officer. A refugee from Syria or Afghanistan, arriving by sea in Greece or Italy, may face months or years of bureaucratic limbo, detention, and uncertainty. The same border that is effectively open to one is practically closed to the other. This selectivity is not an accident; it is a feature. Borders have always been shaped by class, race, religion, and political considerations as much as by geography.

The hierarchies embedded in border regimes are as old as borders themselves. In the mercantilist thinking of seventeenth- and eighteenth-century Europe, states welcomed foreigners who brought capital, skills, or useful knowledge—the so-called "productive" migrants—while excluding or expelling those deemed burdens on the public purse. The distinction between the desirable and the undesirable migrant was never stable, but it was a permanent feature of policy debates. By the nineteenth century, it would acquire new dimensions, as industrial states sought large numbers of unskilled laborers for mines, factories, and construction projects while simultaneously worrying about the social costs of immigration and the political risks of ethnic diversity.

In the twentieth and twenty-first centuries, these tensions have only intensified. The expansion of international human rights law, including the 1951 Refugee Convention, created a legal framework that obligated states to protect people fleeing persecution, regardless of their economic usefulness. Yet the implementation of that framework has always been contested, shaped by domestic politics, economic cycles, and the perceived security environment. The result is a patchwork of rules, exceptions, and ad hoc measures that reflects the competing pressures on modern border policy more honestly than any single principle ever could.

Thinking Historically About Borders

It is tempting to view the history of European borders as a story of progress—from the porous, vaguely defined frontiers of the ancien régime to the rational, well-policed borders of the modern state system. And there is some truth to that narrative. The standardization of passports, the creation of professional border police forces, and the codification of citizenship laws all represent genuine advances in administrative capacity. They have also made possible the extraordinary degree of international travel and exchange that characterizes contemporary Europe.

But there is another story to tell, one in which hardening borders produced new forms of vulnerability and exclusion, and in which the very idea of a "natural" border—whether the Rhine, the Danube, or the Urals—was used to justify conquest, ethnic cleansing, and war. The twentieth century, in particular, is littered with examples of borders that were drawn with the best geopolitical intentions and that then became instruments of oppression. The Iron Curtain, which divided Europe for four decades, was not merely a security barrier; it was a statement about the kind of societies that could and could not exist on each side of it. When it fell in 1989, the euphoria was real, but so were the anxieties about what open borders would mean for labor markets, social cohesion, and national identity.

Those anxieties have not gone away. They have resurfaced in debates over Schengen, over the Dublin Regulation, over the construction of fences along the borders of Hungary and Greece and Spain, and over the willingness of European states to accept refugees from conflicts in the Middle East, Africa, and beyond. To understand these debates, we need more than a sense of the current political climate. We need a longer view—one that reaches back to the eighteenth century and traces the continuities and ruptures that have shaped the Europe we live in today.

That longer view is what the chapters ahead offer. Each one takes a period, a set of policies, or a particular migration corridor and examines it in detail, using the interplay of demographic data and individual stories to bring patterns to life. But the conceptual vocabulary introduced here—borders as institutions, mobility as a constant, nationhood as a contested project—will recur throughout the book. They are the lenses through which we see the past, and, whether we realize it or not, the lenses through which we understand the present.