Poissy

Not to be confused with Passy or Roissy.

Poissy
Commune
Coat of arms
Location (in red) within Paris inner and outer suburbs
Location of Poissy
Poissy Location within France Poissy Location within Île-de-France (region)
Coordinates: 48°55′46″N 2°02′44″E
Country	France
Region	Île-de-France
Department	Yvelines
Arrondissement	Saint-Germain-en-Laye
Canton	Poissy
Intercommunality	CU Grand Paris Seine et Oise
Government
• Mayor (2022–2026)	Sandrine Berno Dos Santos
Area 1	13.28 km2 (5.13 sq mi)
Population  (2023)	40,983
• Density	3,086/km2 (7,993/sq mi)
Demonym(s)	Pisciacais (masculine) Pisciacaise (feminine)
Time zone	UTC+01:00 (CET)
• Summer (DST)	UTC+02:00 (CEST)
INSEE/Postal code	78498 /78300
Elevation	17–171 m (56–561 ft) (avg. 27 m or 89 ft)
1 French Land Register data, which excludes lakes, ponds, glaciers > 1 km2 (0.386 sq mi or 247 acres) and river estuaries.

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Poissy (French: [pwasi] ^ⓘ) is a commune in the Yvelines department in the Île-de-France region in north-central France. It is located in the western suburbs of Paris, 23.8 km (14.8 mi) from the centre of Paris. Inhabitants are called Pisciacais in French. With about 41,000 inhabitants, Poissy is the 5th most populated commune in Yvelines.

Poissy is one of the oldest royal cities of Île-de-France, birthplace of Louis IX of France and Philip III of France, before being supplanted from the 15th century by Saint-Germain-en-Laye. In 1561, it was the site of a fruitless Catholic–Huguenot conference, the Colloquy of Poissy.

The area was known for the early car maker Automobiles Gregoire, and since then a number of companies including Simca and Peugeot, have produced vehicles at the Poissy Plant. From 1961 until 1991 the Simca Poissy engine was made there.