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 . has a history as a
left-wing stronghold, belonging to the (red belt) of
Paris. The
French Communist Party has maintained a continued strong presence in the department, and still controls the city councils in cities such as , and . Until 2008, and 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 general council (while the Communist Party gained a majority in and lost it in 2015). A commune of , , was the scene of the death of two youths which sparked the nationwide
riots of autumn 2005. In October and November, 9,000 cars were burned and 3,000 rioters were arrested. In 2017, the area was the location of 18% of all drug offences in metropolitan France. When two suspects (known criminals from the department) were arrested in the
2025 Louvre robbery it was noted by
The Guardian to have the highest poverty and crime rate in mainland France. == Demographics ==