Transnationalism as a research program has emerged in the social sciences since the 1990s. It refers to studies concentrating on social relations and groups that extend across the borders of nation-states. Referring to the degree of density and durability of such social interactions, often transnational social relations, social fields, and social spaces, are distinguished. Transnational families and transnational organisations are of particular relevance. The global, and even increasing significance of economic, social, cultural, and political remittances reflect the societal reality of transnational life.

By its very nature, international migration as a cross-border movement of persons always includes the travelling of ideas, culture, and artifacts as social, political, cultural, and economic resources. As opposed to classic migration theories and the methodological nationalism often related to this, transnationalism assumes that social relations, fields, and spaces could span different places and locales across nation-states, and by this they could structure social life locally and transnationally.

Transnational social life and realities, as well as transnationalisation as a scientific concept, has had a substantial impact on how to approach migration and integration. If transnational social relations and transnational social spaces are of relevance and have momentum on their own, then migration theories and migration policies have to take into account that nation-state-based units of analysis and of political intervention are only of limited application. Cross-border migration dynamics can neither be explained, nor be managed or controlled without taking into account the drive of transnational social realities. Scientific migration research has to be organised transnationally, and migration policy measures have to be transnational as well. The understanding and approach to integration also has to shift from single and simple assimilation, to more complex multidimensional and multi-local belongings.

1 Key Concepts and Theories

The term transnationalism first gained relevance in social sciences during the 1990s. It refers to social relations and groups that extend across the borders of nation-states. Transnationality is used to address a specific quality of social phenomena such as power or social inequality. While transnationality refers to characteristics of socially relevant objects of study (like families, organisations, infrastructures, social mechanisms, money flows), transnationalisation focuses on the process and the making of social relations and textures spanning across national borders. The focus on transnationalism, transnationality, and transnationalisation is not meant to imply that nation-states are less important, let alone dying out—as is assumed in some concepts of globalisation. On the contrary, the term transnational is actually based on the idea that nation-states still organise and structure major parts of social life, but that they are no longer the exclusive containers of the social.

In this chapter, we focus on transnationalisation as a process of increasing social, cultural, economic, and political relations and interactions between locales across the borders of nation-states and national societies. From a social science perspective, transnationalisation leads to and is sustained by pluri-local cross-border social spaces at the micro, meso, and macro level. At the micro level, transnationalisation refers to habitual and accountable patterns of transnational perception and action in everyday life (such as telecommunication, shipment of goods or sending of money, and information seeking across borders). At the macro level, it includes social institutions as complex programs of routines, rules, and norms that increasingly structure significant terrains of life and span different countries (such as transnational educational careers or labour markets). Finally, at the meso level, transnationalisation is linked to the growth of organisations as stable and dense loci of cooperation with rules of membership, given structures and processes, and stated goals; transnational organisations span over different countries without having a clear and unique headquarters of resources and power.

Concerning the strictness of the use and definition, there are three major understandings of the terms transnationalisation and transnational. In a broad sense, they are used to address all socially relevant phenomena and processes that extend across the borders of nations and nation-states. Here, the notion of transnational and transnationalisation is used in the same sense as the terms international and internationalisation or similar to the term cross national. Examples are speaking of the transnational structure of the internet and of fast-food chains (although their technical or power resources might be highly concentrated). A second understanding of transnational and transnationalisation takes a somewhat narrower social science perspective and refers to the strengthening of social relations in interaction itself. Here it is not the material infrastructure of fiber optic cables of the internet, but the social practice of cross-border interchange and mobility, as in transnational emailing, phoning, and traveling. Transnational relationships are distinguished from inter-state and inter-governmental ones in the sense of the sub-discipline of international relations in political science. Transnationalisation here means the intensification of the social interaction not of states or big corporate actors, but of individual actors such as migrants, and of collective actors such as Greenpeace. In this broader sense, the terms transnational and cross-border are interchangeable. Transnationalisation here is used to distinguish social realities, and relations and movements “from below” as opposed to corporate and state “globalisation from above” (Smith & Guarnizo, 1999).

The third, and even narrower sense of transnationalisation refers to the extension and intensification of social relations and social entities that are nested pluri-locally in different nation-states and span across national societies without having a definite ‘headquarters’. Transnational families, transnational organisations, and transnational social institutions are examples of such transnational social units at micro, macro, and meso level. These social units are not just ephemeral encounters, events, or relations, but dense and durable social entanglements as social networks or social spaces. In a quite restricted sense the term transnationalisation is used to distinguish this specific concept from other forms of cross-border phenomena and processes like globalisation, mondialisation, cosmopolitanism, diasporisation, supranationalisation, and glocalisation (Pries, 2005).

The suitability of the terms transnational, transnationalisation, and transnationality, as well as of the research program of transnationalism, depends on the existence of nation-states and national societies - for anything transnational can exist only as long as there are nations which can serve as referents of the term. In this sense transnationalisation is used in deliberate contrast to the concepts of de-territorialisation, de-spatialisation, liquefaction, or virtualisation according to which geo-spatial boundaries are becoming less and less important. At the same time, the concept of transnationalisation is also used to counter “methodological nationalism” as the assumption that national societies, as defined by the boundaries of nation- states, are/or should be the main units of analysis in social science (Wimmer & Glick Schiller, 2002).

2 Key Studies at Micro, Meso and Macro Level

Transnationalisation as a research program is neither related to a specific social theory nor is it such a theory in its own right. At its beginning there were mainly anthropological and sociological studies departing from “thick descriptions” (Geertz, 1973) of migration processes and its contexts. Transnationalism research first concentrated on the micro level of families and households. It then extended to analyse transnational organisations at a meso level and transnational societal institutions at a macro level.

2.1 Transnationalism, Migration, and the Family

Pioneering cross-border research found long-term family relations between places of migrants’ origin (like Mexico or Caribbean countries) and places of migrants’ arrival like the USA. In the process of migration, the social relations of daily or weekly transnational communication, of sending money, tinned food and electronic devices, and of personally moving, did not decrease or thin out during the life course or from one generation to the next, but dense transnational communities stabilised based on families and social groups; in family and community chains tortillas, beans, and chilies were brought to the USA and money was sent to households in Mexico (Kearney & Nagengast, 1989). Between the Dominican Republic and the USA there existed long term circular migration movements according to the conditions of labour markets and family needs; gender and family roles shifted and led to constant renegotiation of power structures between different persons and groups of transnational families (Grasmuck & Pessar, 1991).

Contrary to the classic model, migration did not lead to changing definitely from one national container (Mexico or Dominican Republic) to another national container (USA), but social life spanned for generations between and above nation-states. In a seminal reader, four basic assumptions of transnationalism were defined: (1) transnational migration is inextricably interwoven with global capitalism and the capital-labour-relations as reflected in transnational labour markets; (2) transnationalism is a process in which migrants produce their own transnational social fields in everyday life; (3) social science concepts of ethnicity, race or nation divert from transnational phenomena; (4) transnational migrant as transmigrants are confronted with related national concepts of race, ethnicity or citizenship (Glick Schiller et al., 1992; Basch et al., 1994). Beyond transnational families, transnational communities could stabilise by collective transnational action like organising water or health infrastructure; migrants in the USA could buy a used ambulance vehicle and bring it to a local village in Mexico in order to establish a first aid chain (Smith, 2006). By long term transnational family relations, power and gender structures change at household and community level (Goldring, 1997).

Although transnational studies at the micro level of families flourished since the 1990s, much empirical evidence could be found for earlier periods. Smith (1997, 2001) analysed the durable transnational relations of Italian and Swedish Migrants to the USA that date back to the nineteenth century and included weekly letter interchanging or control of brides-to-be by regular correspondence with relatives of villages in the USA and Italy or Sweden. Already the groundbreaking study The Polish Peasant in Europe and America of William Thomas and Florian Znaniecki, first published between 1918 and 1920, revealed the complex, intensive, and long lasting interrelations between Polish families and villages and the Polish migrant communities in US-American cities (Thomas & Znaniecki, 1958). Transnational relations were also developed based on the massive forced migration of Jews, socialists, unionists, homosexuals and others, who were persecuted by the Nazi regime in Germany and Austria or after the Civil War in Spain (Pries & Yankelevitch, 2019). Including artists and other professionals and not counting their family members, “about 12,000 intellectuals lost their jobs and were eliminated from Germany’s social and cultural life” (Krohn, 1993, p. 11). In total, since 1933, around half a million persons directly affected had to flee the Nazi regime; many of them established transnational lives after World War II (Krohn, 2011).

2.2 Transnationalism, Migration, and Organisations

From the very beginning of transnationalism research, the meso level of organisations developed based on the study of transnational hometown associations as organisations whose members originate from the same region of origin and join as migrants in the country of arrival in order to provide support to their home localities. Originally set up mostly as cultural or social organisations to foster certain traditions from the homeland and to maintain close ties, these transnational organisations have grown in influence in recent decades, developing political agendas and engaging politically, for example, in their fight for political representation in their countries of origin and of arrival. In a large-scale study, Orozco and Lapointe (2004) examined over 100 of such Mexican hometown associations, focusing on their activities, organisational history, and their structure and partnerships with other organisations in order to develop further typologies and a more nuanced understanding of these organisations.

Portes et al. (2007) especially broadened the horizon of transnational research on migrant organisations by examining the interrelationship of transnational migrant organisations and the migrants’ integration in the country of arrival. By comparing 90 Colombian, Dominican, and Mexican migrant organisations in the USA and their philanthropic projects in their corresponding countries of origin, they found a significant level of civic, philanthropic, cultural and political transnational activities among these organisations. Given their role in development projects in countries of origin, these organisations were also attracting the attention of sending states. In showing that “contexts of exit and reception determine the origin, strength, and character of transnational organisations” (Portes et al., 2007, p. 276), they analytically connect both the circumstances of leaving one’s country of origin (like labour migration or forced migration) and the reception in the country of arrival, with the likelihood and design of collective engagement in transnational migrant organisations. They conclude that there is a higher likelihood of engagement among migrants who reside in the country of arrival over a longer period, as well as those with higher levels of education compared to those who do not fulfil these criteria.

Studies on transnational migrant organisations first focused on Latin American migration to the USA, especially under the focus of so-called hometown associations (more recently e.g. Strunk, 2014; Bada, 2014; Rivera-Salgado, 2015; Duquette-Rury & Bada, 2017), but also on transnational migrant organizations between African and European countries (Dumont, 2008; Lacroix, 2018) or Turkish migration in Europe (Caglar, 2006; Pries & Sezgin, 2012). In the European context, Ostergaard-Nielsen’s (2003) study on Turkish organisations in Germany focuses on political engagement and lobbying rather than development work. She shows how these organisations address governments and institutions in the country of origin as well as in the country of arrival. She provides a typology of political practices of transnational migrant organisations by differentiating transnational immigration politics, homeland politics, diaspora politics, and translocal politics. In a similar vein, Koopmans and Statham (2003) study the political demands of migrant organisations in various European countries and explain how European citizenship and models of integration may influence transnational claims-making. Using a case study of Turkish hometown associations in Germany, Caglar (2006) also highlights power structures in proposing a framework that takes into account specific relations of spaces and state policies.

Some studies on transnational organisations in the context of migration explicitly relate to the broader tradition of organisation studies in general. For profit organisations Bartlett and Ghoshal (1989) differentiated four ideal types of organisations that are active across national borders. According to the degree of centralisation or decentralisation of power and resources and of strong or weak cross-border coordination of the organisational units, they distinguish global organisations (centralised and strong coordination), multinational organisations (decentralised and weak coordination), focal organisations (centralised and weak coordination) and transnational organisations (decentralised and strong coordination). In this more specific understanding of transnational organisations Pries (2008, 2012, with Sezgin) studied transnational migrant organisations between Germany and Turkey analysing (1) the mobilisation and distribution of resources (including membership, money, and infrastructure) between places and countries; (2) the main goals, themes, and demands (including subjects, target groups and allies); (3) the arrangement of external activities (including publication strategies, public activities, and events); and (4) the coordination and control of internal activities (including communication flows, meetings, internal elections, and decision-making).

More recently, greater efforts have been made to connect research on International Relations (IR) with migrant organisations. Dijkzeul and Fauser (2020) presented a variety of studies focusing on different roles of migrant organisations in lobbying for portable migrant labour rights (Bada & Gleeson, 2020), promoting faith and secularism (Carpi & Fiddian-Quasmiyeh, 2020), and in conflict management and peacebuilding (Zach, 2020). In stark contrast to methodological nationalism and realism in traditional IR theory, the authors underline that transnational organisations can leverage their influence and strength by building and maintaining organisational networks, and thus have to be considered as powerful players in lobbying for their interests in the political arena (Dijkzeul et al., 2020). However, in recent years, a great part of studies on transnational migrant organisations looking at other world-regions has also emerged (Okamura, 2014; Joseph et al., 2018).

2.3 Transnationalism, Societies, and the Nation-State

Transnationalisation is by no means a new phenomenon. Social relationships and social spaces that extend beyond the boundaries of the prevalent national forms of socialisation have always existed. Examples include traveling adventurers and itinerant traders in antiquity, religious networks, major organisations that have spanned the boundaries of principalities and feudal realms since the beginning of Catholicism, and economic service providers that connected large trading cities and continents such as the Fugger family and the Hanseatic League. When, in the eighteenth century, ideas of national units in the form of modern nation-states and national societies began to take hold, many of the historical structures of social space which had come to extend beyond the territorial boundaries that then began to separate different social units, became transnational in a wider sense of the term. Consequently, the nationalisation of certain processes such as the emergence of social classes and the concept of public education has always been accompanied by the continued existence of social practices such as long-distance trade and trans-regional royal intermarriage.

Transnationalisation, when understood in this broader sense and at a macro level, depends on the emergence of modern national societies that are demarcated by nation-state boundaries. In Europe there has emerged the concept of nations as “imagined communities” (Anderson, 2006). This idea refers to the formation of collective identities which provide the structure for membership rights that are relevant to the lives of the members of these communities. These privileges include the rights to housing, education, work, freedom of movement, and social security. After centuries of religious conflict between Catholics and Protestants, the Peace of Augsburg in 1555, and, more, the Peace of Westphalia in 1648 established the binding principle of cuius regio, eius religio, which required that all those who lived within the territorial boundaries of a sovereign state have the same religion—that of their ruler. This Westphalian order culminated in the twentieth-century concept of national societies as relatively culturally homogeneous units which are clearly separated in nation-state containers. There should be only one homogeneous social space within a given geo-graphical territory. All residents should have the same language, religion, culture, ethnic identity, and tradition, and every national society, in its role of an imagined social unit, should have one, and only one, geographic or territorial point of reference.

This idea of national societies as culturally homogeneous units has been the guiding principle, though not the reality, of social development in Europe in the modern age. The embedding of all central aspects and mechanisms of socialisation in national containers was one of the main pillars of modernisation—alongside individualisation, urbanisation, secularisation, rationalisation, and functional differentiation. In the twentieth century, modernisation was analysed mainly as the diffusion of social values, practices, and institutions from the ‘more developed’ nation-states to the ‘less developed’ ones—for example, as the dissemination of rationality, democracy, social welfare, and secularity from the West to the rest of the world. Such differentiating between modern and traditional, between advanced and less developed had legitimised colonialism and imperialism for centuries. It was against all empirical evidence of religious, cultural, political, and social diversity during all the history of mankind and against the fact that spatial mobility and migration are inextricable building elements of human history. This is why the critical reflection of methodological nationalism as “the assumption that the nation/state/society is the natural social and political form of the modern world” (Wimmer & Glick Schiller, 2002, p. 302) is so important in migration studies.

Ulrich Beck, drawing on the ideas of Wimmer and Glick Schiller, proposed to replace the previously dominant perspective of methodological nationalism by what he calls “methodological cosmopolitanism”, a new perspective which focuses on “the increasing interdependence of social actors across national boundaries” (Beck, 2004, p. 30). Even more radically, John Urry argued that the focus of sociological research should move away from “the ‘social as society’ to “the ‘social as mobility’” (2001, p. 2). Cosmopolitanism is here dealt with as a normative project of a human world society or as a universal and unilineal tendency. Therefore the alternatives of either globalism or methodological nationalism are not adequate. Global, transnational, and national social relations and entities are of increasing importance at the same time. Transnationalisation is only one, but a crucial component of a more complex multi-level model of relating systematically social spaces—such as family life, working space, religious practices, collective identities, claims making, and social movements—to their corresponding—local, national, regional, transnational, global—geographic configurations (Pries, 2008; Vertovec, 2004). During the last three decades, transnationalism as a research program in this sense has produced a wide range of empirical and conceptual studies (Vertovec & Cohen, 1999; Khagram & Levitt, 2007; book series like Routledge’s Research in Transnationalism and new journals like Global Networks).

Widening the focus of international migration research to transnationalization processes allows to better understand why during the last two centuries cross-border migration increased faster than world population and how this impacts social life all over the globe. The substantial role of economic remittances—received in one way or another almost by one out of eight inhabitants all over the world—could not be explained without referring to the dense transnational social networks of migrants. From 1990 to 2019 remittance inflows to Low-and-Middle-Income Countries increased worldwide from some 29 to more than 548 billion US-Dollars, that is, by some 1900% (KNOMAD, 2019, p. 3). During the same period, the world population grew by only 45% (from 5.3 to 7.7 billion) and international migrant stock by 84% (from some 153 to 281 million).Footnote 1 “No longer do those who emigrate separate themselves as thoroughly as they once did from the families and communities they leave behind. [...] We can no longer divide ourselves so easily into ‘countries of origin’ and ‘countries of destination’ since, to one degree or another, many countries are now both.” (UN, 2006, p. 6). Transnational activities could extend the scope of opportunities and options for work and living, at the same time they tear families and social groups apart. Such social disruption can be alleviated by transnational social practices of communication, of sending money and other goods and of occasional visits. By this, transnational activities in the context of migration lead not only to economic but to social remittances (for conceptual revision Levitt & Lamba-Nieves, 2011; for social remittances in Europe Grabowska et al., 2017; for the transnational travelling of religions in Latin America Pries & Bohlen, 2019).

3 Desiderata of Transnationalism and Migration Research

In the twenty-first century, the transnationalism approach has been crucial for migration research for several reasons. First, it changes our scientific understanding of migration dynamics. Considered through a transnational lens, migration, once initiated, causes new migration through changed expectations in the regions of origin and new, migration-related demand structures in the regions of arrival. Through economic remittances and social, cultural, and political transmittances (Pries, 2020), regions of emigration and of immigration remain connected to each other. Migration processes essentially follow the logic of collective action of the migrants in their local, national, and transnational relations and social spaces. Measures of restrictive border controls often lead to less flexible labour market adjustment and to higher life risks for the migrants. Ecological problems, armed conflicts, and poverty are increasingly blurring the boundaries between labour migration and forced displacement, voluntary and forced migration, regular and irregular migration, to mixed migration flows. Modern communication and transport facilities can promote transnational migration with multiple locations of the migrants in the country of origin and the country of arrival. As a rule, migration is not a rational one-off decision, but a longer-term process of transnational “muddling through”, in which goals, schedules, identities, and historically developed transnational social network structures are iteratively and successively developed.

This leads to a second reason for strengthening transnational perspectives in migration research. As a general pattern, the field of migration studies and of integration studies are often separated from each other.Footnote 2 But distinguishing four ideal types of migrants could help to connect to different approaches of integration. Once migrants arrive in a country they are often treated either as immigrants that have to assimilate or as commuting, or return-migrants that don’t need integration efforts. The ideal type of immigrants refers to those migrants who have resolutely decided to leave behind their former life and assimilate by beginning a new life with new social entanglements, new fully biographical experiences, and a second process of socialisation by redefining their preferences and expectations built on new resources. Millions of Europeans such as those who left their countries at the turn of the nineteenth to the twentieth century as emigrants towards the Americas in search for better economic and socio-cultural conditions could be considered as such. But almost a third of them—even if not planned from the beginning—returned to their European homelands. They could be considered as ideal-typical return migrants. This qualification also holds for a great part of the so-called guestworkers in Europe. They are perceived—and often perceive themselves—as strongly willing to return to their country of origin and their former life. Return migrants maintain strong social entanglements to the places of their origin, they do not feel the necessities or are not expected to learn the languages and socio-cultural norms of the places of arrival. They maintain their former socialisation and are not willing and not invited to renegotiate their preferences and expectations.

Meanwhile, while in the case of immigrants and return-migrants there is a strong and clear orientation to either the country of arrival or the country of origin as a basic frame of reference, this is not the case for the two ideal-types of Diaspora-migrants and transmigrants. Diaspora-migrants define themselves in the frame of reference of a specific ‘land of promise’, but are open to accept or negotiate to live in other places.Footnote 3 They manage social entanglements and experiences and socialise in different places, they develop hybrid preferences and expectations and combine resources of different places. The classic example are religious communities like the Jewish or the Alevi Diasporas distributed all over the world. But we could also include diplomatic corps or business organisations maintaining strong social ties to their home country or headquarters as ‘land of promise’. Diaspora migrants experience the places they are living normally as spaces of suffering or of mission.

Finally, transnational migrants or transmigrants typically do not distinguish by this way between region of origin and of arrival, but develop an ambiguous and hybrid mixture of adherence and belonging. They sustain differences to the region(s) of origin and of arrival. Transmigrants live—mentally and often physically—between and across places in different countries. Maintaining their lifeworld, their stocks of knowledge, interpretative patterns, and biographical projects for the future are in some parts related to their countries of origin or the places of their ancestors, but in other parts their lives take new entanglements, experiences, socialisation, preferences, expectations and resources. Examples of such transmigrants could be found in social groups of artists, sportspersons, managers, or politicians, but also in transnational families of labour migrants and of forced migrants all over the world (as examples for the Americas see Levitt, 2001; Smith, 2006; for Europe see Østergaard-Nielsen, 2003; Mau, 2010; for Asia see Ong & Nonini, 1997; Westwood & Phizacklea, 2000; Jackson et al., 2004).

As the transnationalism approach leads to a better understanding and explanation of migration and of integration and the interrelations between both, it finally also helps to calculate opportunities and challenges for migration policies. Taking transnational social relations and transnational social spaces seriously offers some strong limitations but also some new leverages for policies and politics. On the one hand, migration processes can only be partially controlled and steered by direct political means. For instance, efforts to close or perform stricter controls on national borders of migrants often fails due to the momentum of migration dynamics that is based on the transnational social spaces. Stricter border control at the Mexican-USA border led to “caging effects” of transnational migration.Footnote 4

During the 1990s, the transnationalisation approach introduced a fourth approach towards thinking about migration. According to this, migration is much more than container hopping from one national society to another—be it assimilationist or multicultural. Migration processes always create cross-border social ties between groups in different places and national societies. Transnational social relations and transnational social spaces include the interchange of resources like sending money or other goods, but also communications by regular phone calling, sending videos, or sharing social media spaces in Facebook or Instagram. By this, everyday life is not concentrated in just one place but spans multiple locales across national borders. To understand and explain the lifeworld of migrants, we have to relate to the places they or their ancestors lived before, to the places they are currently living, and the places they are including in their visions for their future life. This is especially true for forced migrants given that they normally begin to negotiate their social belonging after their flight.

The concept of national societies—of entities defined by the territorial boundaries of nation-states—might be regarded as an historical invention, a principle conveniently invoked to justify nationalism, racism, and violence. But under certain circumstances national societies have also proved to be reliable frameworks for individual and collective rights, for social welfare, political stability, and accountability. Transnationalisation began at the same time as and as a by-product of the national closure of the social. Besides economic relations and value chains, the cross-border dissemination of cultural products like movies, political movements, and non-profit organisations like Greenpeace, migration is a crucial driver of transnationalisation.

During the second decade of the twenty-first century, cross-border migration increased eight times faster than world population; forced migration even doubled from 40 to 80 million persons. More than 10% of the world population depend on remittances payments of migrants (IOM, 2020). Cross-border migration might lead to immigration or to return migration—sometimes it is a kind of Diaspora migration—but it always induces also transnational migration and the transnationalisation of social spaces in general. The ‘national’ in transnationalisation underlines that both nation-states and national societies continue to shape social reality. Nation-states and national societies shape the ways in which social collectives perceive themselves and others (collective identities), structure political groups (parliaments, governments, political parties), configure everyday life (families, leisure), work and employment (companies, unions), and organise social welfare (healthcare, pension funds). However, many of these aspects of social entanglements and socialisation processes transcend the borders of national societies.

Transnationalism and transnationalisation capture some aspects of these border-crossing phenomena. Labour market conditions and dynamics, socio-cultural belonging and identities, integration policies, and social welfare, and claims-making processes and political interest organisation are all aspects of social life that have a transnational dimension and show up elements of transnationalisation. Transnational social spaces raise questions of multiple membership rights, from social security to citizenship. Social integration can no longer be restricted to a single place but rather must be seen as an open and unpredictable social process of increasing interconnectedness of persons on local, regional, national, supranational, global, glocal, diasporic, and transnational levels. Transnationalisation also increases the risk that only actors who can articulate themselves appropriately or who have strong lobbying power will be able to make themselves heard on the various levels. Still, transnationalisation should not be regarded as a threat to social stability and nation-state control, even if transnational crime, from tax evasion to human and arms trafficking, are an increasing challenge. Above all, transnationalisation may bring about new forms of social diversity that extends across different places and social cohesion beyond fragmentations that are limited to one place.

Transnationalism as a research program is crucial for any kind of migration studies. It opens and connects migration research to the global questions of social sciences in the twenty-first century (Faist, 2019). As it is not a sociological theory in its own right, but has to be combined with and grounded in social science concepts according to the subject and objectives of study, it therefore invites multiscalar and multi-dimensional analysis. Transnationalism invites us to deepen our understanding of space in the dimensions of geographic and social spaces.