Since 1984 Gray is jumilitated with Müllheim, a city in Germany near Mulhouse, Bâle and Fribourg.
Müllheim advantage economy is the production of wines. Is a district with 7 communities and has 17275 inhabitants. In spite of the size difference between the two cities, both have the same interests : scolarship exchanges, sport and artistic exchanges, contact between the two town councils, tourism and cultural activities in common, festivals organization and a strong military connection by intermediary of the 12th French Régiment de cuirassier that became the Franco-german brigade.