The Danish–German border was drawn 100 years ago. This chapter focuses on four cities: Flensburg, Niebüll, Padborg, and Tønder. Flensburg lost half of its hinterland in 1920, when the border was drawn immediately north of the city. Tønder became a Danish border city, losing its southern hinterland. This led to the elevation of an additional border city south of the new border, Niebüll. Previously just a railway intersection, it became the new county seat for the rest of divided Tønder County, Landkreis Südtondern. Padborg evolved from a hamlet to a border train station, and later to a logistics hub. Demographic development from a two centuries’ perspective already demonstrates the negative effects on Flensburg and Tønder since becoming border cities. Padborg, on the other hand, profited from its central position at a key border infrastructure. The process of European integration, especially the implementation of the Schengen regime of open borders, has offered new opportunities for border city development, not least by refocusing on the border as a meeting point and a resource. All four cities demonstrate how the border has impacted their development, how not only spatial planning strategies, but also imaginaries and narratives to align with or overcome the border have been attempted, with and without success.