Ille-et-Vilaine Ill-e-Vilaenn (Gallo) Il-ha-Gwilen (Breton)
Department of France
Prefecture building in Rennes
Flag Coat of arms
Location of Ille-et-Vilaine in France
Coordinates: 48°10′N 01°40′W / 48.167°N 1.667°W / 48.167; -1.667
Country	France
Region	Brittany
Prefecture	Rennes
Subprefectures	Fougères Redon Saint-Malo
Government
• President of the Departmental Council	Jean-Luc Chenut[1] (PS)
Area 1
• Total	6,775 km2 (2,616 sq mi)
Population  (2023)[2]
• Total	1,120,666
• Rank	21st
• Density	165.4/km2 (428.4/sq mi)
Time zone	UTC+1 (CET)
• Summer (DST)	UTC+2 (CEST)
ISO 3166 code	FR-35
Department number	35
Arrondissements	4
Cantons	27
Communes	332
^1 French Land Register data, which exclude estuaries, and lakes, ponds, and glaciers larger than 1 km2

Ille-et-Vilaine (French: [il e vilɛn] ^ⓘ; Gallo: Ill-e-Vilaenn; Breton: Il-ha-Gwilen; lit. 'Ille and Vilaine') is a department of France, located in the Brittany region in the northwest of the country. It is named after its two main rivers, the Ille and the Vilaine. Its prefecture is Rennes, with subprefectures in Fougères, Redon and Saint-Malo. It had a population of 1,120,666 in 2023.^[3]

Ille-et-Vilaine is one of the original 83 departments created during the French Revolution on 4 March 1790. It was created from part of the province of Brittany.

Ille-et-Vilaine is a part of the current region of Brittany and it is bordered by the departments of Manche to the north-east, Mayenne to the east, Maine-et-Loire to the south-east, Loire-Atlantique to the south, Morbihan to the south-west, and Côtes-d'Armor to the west and north-west – France's shortest administrative department boundary at 20 yards (19 metres), although this was not the case with the department boundary. Also the English Channel (la Manche in French) borders the department to the north. It is in Upper Brittany.

The department is named after its two main rivers, the Ille and the Vilaine, whose confluence is in Rennes, the capital of the department and of the region. Other important rivers include:

• the Rance, that borders the department in the north-west and flows to the north, creating a deep fjord before reaching the English Channel on the western part of the coast (named Côte d'Émeraude) between the cities of Dinard and Saint-Malo); the Rance river is connected from the west of the department to the Ille river in the north-west suburbs of Rennes with a navigable channel (then the Ille river is channelized to join the Vilaine up to the center of the city of Rennes);
• and the Couesnon that borders the eastern part of the department and which reaches the eastern part of the coast of the English Channel, in the flat Bay of the Mont Saint-Michel.

The department is moderately elevated above the level of the sea, with many hills; however the central part has a dense network of many tributaries to the Ille or the Vilaine from all around the large basin of Rennes. The elevated hills bordering this basin are covered by several old forests now exploited by men for the production of wood. The basin itself is a rich agriculture area, as well as the north-west of the department near the Rance.

In the extreme south of the department the Vilaine goes through a slower decrease in elevation in a small corridor in the area of the city of Redon; in this area, the Vilaine is known for its frequent floods during its recent history, often because of too-intensive draining of agricultural areas around Rennes (some floods also affected some parts of Rennes up to the 1980s due to incorrect management of old equipment of the canal of Ille-et-Rance). To avoid these hazards within inhabited cities, some natural fields bordering the Vilaine in the south of the department are now left floodable, and works for regulating the level have been done including, small artificial lakes with derivation channels, replanting trees in the basin, better management of forests, and regulating the artificial drains made for agriculture.

The population has grown steadily since the 1960s, reaching 1.1 million in 2023.

Population development since 1801:

Historical population
Year Pop. ±% p.a. 1801 488,846 —     1821 533,207 +0.44% 1831 547,052 +0.26% 1841 549,217 +0.04% 1851 574,618 +0.45% 1861 584,930 +0.18% 1876 602,712 +0.20% 1881 615,480 +0.42% 1891 626,875 +0.18% 1901 614,000 −0.21% 1921 558,574 −0.47% 1936 566,000 +0.09%	Year Pop. ±% p.a. 1946 578,246 +0.21% 1954 586,812 +0.18% 1962 614,268 +0.57% 1968 652,722 +1.02% 1975 702,199 +1.05% 1982 749,764 +0.94% 1990 798,718 +0.79% 1999 867,533 +0.92% 2007 955,846 +1.22% 2012 1,007,901 +1.07% 2017 1,060,199 +1.02% 2023 1,120,666 +0.93%
Sources:[5][3]

Gallo is a historic minority language spoken in eastern Brittany. Gallo and Breton are both studied at the University of Rennes.

• 
  Rennes city centre
• 
  The medieval town of Vitré
• 
  Plage de l'Écluse in Dinard
• 
  Legendary forest of Brocéliande in Paimpont
• 
  Château de Fougères
• 
  The fishing village of Saint-Suliac
• 
  Stone row La Roche aux fées in Essé

• Cantons of the Ille-et-Vilaine department
• Communes of the Ille-et-Vilaine department
• Arrondissements of the Ille-et-Vilaine department
• Saint-Sauveur Abbey Church of Redon

Wikimedia Commons has media related to Ille-et-Vilaine.

• (in French) Prefecture website
• (in French) Departmental Council website
• (in French) Cultural Heritage