Estonia and Finland have centuries of collaboration, mainly between the capital areas of Tallinn and Helsinki that currently account for 2 million inhabitants and USD 76 billion in economic output. The entry of Estonia into the European Union and, since the mid-2000s, a two-hour ferry trip, have...

Hedmark County (Norway) and Dalarna County (Sweden) are both rural, with the border being remote from regional centres. The total population of less than half a million inhabitants spans across almost 58 800 km², with an economic output of USD 22 billion. Efforts to support collaboration at the...