Sister Cities, Stronger Democracies: Building Resilience Beyond Borders

Democracies worldwide are facing increasing pressure. Relationships between Europe and the United States have shifted in ways that seemed unthinkable just a few years ago. Since Donald Trump’s second presidency began, 100 days ago, transatlantic relationships have faced renewed strain nearly every single day.

Trump’s administration's scepticism towards NATO, erratic foreign policy, and emphasis on “America First” have weakened trust amongst European allies. His reluctance to commit firmly to Ukraine’s defence and his criticism of continued US military and financial support have created uncertainty across the Atlantic. This has forced European nations to reevaluate their security strategies and question the reliability of the US as a long-term partner. 

However, these challenges highlight - not diminish - the importance of strong transatlantic ties. In an era when national-level leadership can shift dramatically and behave unpredictably, it becomes even more vital for local governments, civil society, and multilateral institutions to uphold and deepen collaboration across borders.

In my role as Deputy Mayor in Frankfurt, I am responsible for international affairs. As such, my office builds and sustains subnational relations across the globe. Subnational relations refer to the diplomacy and cooperation that occurs not between national governments, but between local or regional entities, such as cities or states. These relationships can include economic as well as cultural exchange or academic collaboration. Oftentimes they go beyond the work of public administrations and are pillared by civil society engagement.

Frankfurt has a sister city in the United States: Philadelphia in Pennsylvania. In commemoration of  the 10-year anniversary of this partnership, I travelled to visit our colleagues in the “City of Brotherly Love” at the end of March, with an official delegation . This visit took place just days after the travel guidance issued by the Germany Foreign Office was revised, prompted by the detention of three German citizens, who were held in custody pending deportation after attempting to enter the United States. 

In 2024, I traveled to Detroit, Michigan, as part of the Young Leaders’ Conference of the Atlantik-Brücke, an organisation dedicated to strengthening transatlantic relations. At the time, just eight months before the Philadelphia trip, the thought of being denied entry to the US had never crossed my mind. But circumstances had changed. Having previously shared content on social media openly critical of Donald Trump, the prospect of facing consequences for my political expression now felt unsettlingly real. It struck me as profoundly ironic - and deeply troubling - that I might be refused entry to the "land of the free, home of the brave" for exercising the very freedoms it so proudly claims to uphold. Luckily, the entry went smoothly. 

Delegation visits often carry a formal tone, but it is the informal moments - the human connections beyond official titles and the exchange with civil society - that leave a lasting impression and bring the spirit of a sister city to life. This visit was no exception. The encounters that resonated with me most deeply were not those in conference rooms, but rather the spontaneous conversations, like the one I had with an Uber driver, who spoke with a mix of frustration and weariness about the state of politics in his hometown, a place he had never left. His reflections on deserted city centres, the steady disappearance of local shops, a growing sense of unease in certain neighborhoods, and the feeling that political leaders were distant and out of touch could just as easily have come from a resident of Germany. It struck me how universal such sentiments have become, echoing quietly but persistently across democratic societies. Perhaps what we’re witnessing is not just local discontent, but a deeper, shared longing for connection, representation, and renewal.

A visit to a local school engaged in student exchanges with partner schools in Frankfurt offered a glimmer of hope for a brighter, cooperative future. Student exchanges are the most familiar and tangible form of what is often called subnational diplomacy. It is also one of the most powerful. These exchanges create opportunities for young people to step, if only briefly, into the lives of their peers abroad, to experience different living conditions, family dynamics, and educational systems firsthand. Such moments can be transformative. They often become the seeds from which global citizens grow - individuals who are instinctively open to the world, attuned to cooperation, and capable of empathy that transcends borders.

Beyond the human connections, there are compelling structural reasons why subnational diplomacy is essential for vibrant, forward-looking cities and communities. Local governments frequently exchange ideas and best practices to tackle shared urban challenges. In Philadelphia, for instance, we learned how city offices proactively reach out to residents to inform them about their eligibility for social benefits - a common issue in many cities, where the most vulnerable are often the hardest to reach.

At Volt Europa, we practise exchanging the best ideas for more democratic, well-functioning governments every day, with  a network of members working for change all over Europe. And it is crucial that we do so, given that the challenges we face on the local level are mostly the same in every municipality: affordable housing, mobility, climate change, and high quality education for everyone. As urban economies grow increasingly reliant on international networks, fostering cooperation at the local level enables more targeted, scaleable, and pragmatic approaches to policy innovation. Strengthened international, transatlantic and European engagement among cities not only enhances administrative capacity but also reinforces democratic governance, social cohesion, and intercultural competence in a rapidly evolving global context.

To meet these challenges head-on, it is crucial that international relationships are actively nurtured, not just at the national level, but across towns, cities, and regions throughout Europe. Strengthening ties on the local level ensures that cooperation endures beyond election cycles and shifting political climates. It democratises diplomacy by bringing it closer to citizens, fostering grassroots resilience against isolationism and authoritarianism. Local transatlantic partnerships can empower communities to share knowledge, build mutual trust, and develop long-term strategies that defend democratic values, protect human rights, and promote sustainability. In doing so, Europe’s local actors become contributors to the transatlantic alliance, safeguarding it from fragmentation, and ensuring it evolves with the shared needs and aspirations of its people. As the world continues to wrestle with democratic backsliding, the importance of these relationships will only grow. Subnational diplomacy is not an afterthought - it is a frontline defence of freedom, pluralism, and global solidarity.

After returning to Frankfurt, I had just four days to recover before traveling to our partner city, Lviv, in Ukraine, for the opening ceremony of its designation as European Youth Capital - a title the city applied for just days before Russia’s full-scale invasion in 2022. Among the city's young contributors was 21-year-old Yaryna Bazylevych, programme manager at the office championing the bid. She was tragically killed, along with her sisters and mother, when a missile struck their home in September. In a city marked by loss and resilience, I was deeply moved by the strength and hope of Lviv’s people. Their daily courage is a quiet defiance, a promise that light will outlast darkness.

As European Youth Capital, Lviv aims to encourage young people to stay in Ukraine, motivate those who have left to return, and strengthen connections with Europe. To offer practical and not just symbolic support, Frankfurt, along with Lviv and our sister city, Krakow, recently launched the project SheStarts in an effort to support these goals. This cross-border initiative empowers young women from Frankfurt to launch their own businesses by offering support, fostering entrepreneurship and international collaboration among aspiring female founders.

Both visits were a stark reminder for me: subnational ties are not simply symbolic. From Philadelphia to Frankfurt to Lviv, cities are building bridges across borders - bridges strong enough to lift the hopes of peace, solidarity, and shared humanity. And in a fractured world, those bridges matter more than ever.