Located where the Swiss, French and German borders meet, Basel also has suburbs in France and Germany. As of 2016, the Swiss Basel agglomeration was the third-largest in Switzerland, with a population of 541,000 in 74 municipalities in Switzerland (municipal count as of 2018).
The initiative Trinational Eurodistrict Basel (TEB) of 62 suburban communes including municipalities in neighboring countries, counted 829,000 inhabitants in 2007.