Its departmental code is 90, and its prefecture (capital) is Belfort. There is a single arrondissement (Belfort), which is subdivided into 9 cantons and thence into 102 communes.

The administrative district Territoire de Belfort was created under the terms of the 1871 Treaty of Frankfurt. The German Empire annexed almost all of Alsace, but the French were able to negotiate retention of the Territoire de Belfort which thereby was separated from the rest of Alsace (where it had been part of the department of Haut-Rhin). There were three principal reasons for this exceptional treatment:

The Germans agreed primarily because the Prussian military officiers indicated that leaving it in France would give Germany a more defensible border.

After retaining its unique status as a territoire for just over half a century, Belfort was officially recognized as France's 90th department in 1922. France had recovered Alsace three years earlier, but the decision was taken not to reintegrate Belfort into its former department. There was talk of giving it a new departmental name, with suggestions that included "Savoureuse" (after the main river of the new department) or "Mont-Terrible" (the name of a former Napoleonic department embracing parts of Switzerland), but there was no consensus for a name change and the department continues to be known as the Territoire de Belfort.

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