Sites such as Facebook give us the unprecedented ability to form and maintain relationships with people around the world. In this post we explore part of this connected landscape: Europe. Looking at aggregated, anonymized data, we found that in the European continent alone, there exist approximately 5 billion cross-country Facebook friendships.

Figure 1 shows, in aggregate, friendships ties between cities, both within and across country borders. While visualizing the beautiful network of city-to-city friendship connections, we found an interesting trend: year by year, the proportion of new friendships that are international has been growing. Not only that, every August, as Europeans travel on vacation, international friendships get an additional boost.

Finally, we compute, for people currently living in a country, regardless of their or their friends’ country of origin, the number of friends living in a different European country. We observe that the aggregate proportion of international friendships within Europe is higher in states with small populations, measuring 85% in San Marino and Monaco. Switzerland, Moldova, Albania and Cyprus, have between 25-30%. Germany, Belgium, and Iceland have around 15%, and Great Britain, France, Spain, Denmark and Norway have between 10-11%. One of the lowest percentages is for Italy (6%) though with many more Augusts to come, this may change in time.