Seine-Saint-Denis is a French department located in the Île-de-France region. In local slang, it is known as "quatre-vingt treize" (i.e. "ninety-three") or "neuf trois" (i.e. "nine three"), after the official administrative number of the department, 93.
The learned and rarely used demonym for the inhabitants is Séquano-Dionysiens; more common is Dionysiens.
Seine-Saint-Denis was created in January 1968, through the implementation of a law passed in July 1964. It was formed from the part of the (hitherto larger) Seine department to the north and north-east of the Paris ring road (and the line of the old city walls), together with a small slice taken from Seine-et-Oise.
Seine-Saint-Denis has a history as a veritable left-wing stronghold, belonging to the ceinture rouge (red belt) of Paris. The French Communist Party especially has maintained a continued strong presence in the department, and still controls the city councils in cities such as Saint-Denis, Bobigny, Le Blanc-Mesnil and La Courneuve. Until 2008, Seine-Saint-Denis and Val-de-Marne were the only departments where the Communist Party had a majority in the general councils but the 2008 cantonal elections saw the socialists become the strongest group at the Seine-Saint-Denis general council (while the Communist Party gained a majority in Allier).
A commune of Seine-Saint-Denis, Clichy-sous-Bois, was the scene of the death of two youths which sparked the nationwide riots of autumn 2005. In October - November, 9,000 cars were burned and 3,000 rioters were arrested.