Gex is the administrative capital of the Pays de Gex, itself located in the department of Ain, in the Auvergne Rhône-Alpes region, 19 km north-west of Geneva. The city hosts, among others, the Sub-Prefecture of Gex-Nantua and the seat of the Agglomeration Community of the Country of Gex.
The vast municipal area of 32 km² is located on the borders of Switzerland to the south and on the eastern foothills of the Jura massif to the north, to which it is linked by the Col de la Faucille. Crossed by several rivers including the Journans, the town is largely forest (1772 wooded hectares), and if the city has developed at an altitude of 600 m, its highest point exceeds 1600 m.
Already inhabited during the Gallo-Roman era, Gex first depends on the Counts of Geneva before being the seat of a seigneury from the 12th century. Then, with the neighboring communes forming the Country of Gex, the city was annexed to Savoy in the 14th century before being attached to France in 1601. The establishment in 1954 of the European Center for Nuclear Research (CERN) and in 1960 several large international organizations in Geneva contributed to the densification of the urbanization of this entire border area.
In 2019, Gex had 13,375 inhabitants (figures communicated by INSEE).
Its exceptional environment (it is one of the gateways to the Haut-Jura Regional Natural Park and the National Nature Reserve of the Haute Chaîne du Jura), its views of the Alps, the immediate proximity of the Monts Jura resort, in particular, make it an essential stopover for lovers of green tourism and hiking.