Montérégie (French pronunciation: [mɔ̃teʁeʒi]) is an administrative region in the southwest part of Quebec. It includes the cities of Boucherville, Brossard, Châteauguay, Longueuil, Saint-Hyacinthe, Saint-Jean-sur-Richelieu, Salaberry-de-Valleyfield and Vaudreuil-Dorion.

The region had a population of 1,507,070 as of the 2016 census and a land area of 11,132.34 square kilometres (4,298.22 sq mi), giving it a population density of 135.4 inhabitants/km² (350 per sq. mi.).^[1] With approximately 18.5% of the province's population, it is the second most populous region of Quebec after Montreal. The majority of the population lives near the Saint Lawrence River, on the south shore of Montreal.

Montérégie is known for its vineyards, orchards, panoramas, products, and the Monteregian mountains. The region is both urban (second in terms of population in Quebec) and rural. The regional economy is based on agriculture and the production of goods and services. Tourism also makes up a significant portion of the economy.^{[citation needed]}

Jacques Cartier named Mont Royal in October 1535.^[3] Samuel de Champlain built several forts to protect the colonists against the Iroquois from south of the Great Lakes, and against the English, who were colonizing New England to the southeast.

The toponym comes from the Latinized form of Mount Royal, mons regius. Montérégie is named for the Monteregian Hills, which are, in turn, named for Mont Royal (English: Mount Royal). The term for naming the set of hills in the St. Lawrence Plain was originally created in 1903 in English by geologist Frank Dawson Adams to designate a new petrographic province.

Mount Royal on Montreal Island, although outside the Montérégie region, is one of the Monteregian Hills. In addition to Mount Royal, two other Montérégie hills are not located in Montérégie: Mount Mégantic, in Estrie, and the hills of Oka, in the Lower Laurentians.

Montérégie was populated by the St. Lawrence Iroquoian people when the French began to colonize here in the early 16th century. Later colonists found their villages abandoned, and the area controlled as hunting grounds by the nations of the Iroquoian Confederacy based south of the Great Lakes.

Some of the later battles among the European-Canadians that decided the destiny of Canada took place in Montérégie. For instance, in the 1830s, ethnic French patriots rebelled against British government troops.^[4] The Province of Canada (also called a United Canada (French: Canada-Uni)) was formed through the Union Act in 1840 and February 1841, from the former provinces of Lower Canada and Upper Canada.

Originally, the administrative territory of the Montérégie parishes were taken from the territory of the canonical Diocese of Saint-Jean-Longueuil.^{[citation needed]}

The Montérégie has three administrative subregions, each consisting of its own regional county municipalities (RCM) or equivalent territories. The territorial administration of the region was conducted by three regional conferences of elected officers (French: Conférences régionales des élus) (CRE) separate and independent in their territory:

• Longueuil,
• Montérégie-Est (eastern RCMs) and
• Vallée-du-Haut-Saint-Laurent (western RCMs).

Each sub-region was organized in the same way as other administrative regions of Quebec.

The population of both of these reserves are majority-Mohawk, one of the historic Five Nations of the Haudenosaunee, or Iroquois League. Kahnawake was established south of Montreal in 1719 as a mission village. Akwesasne was established upriver by Mohawk leaders and their families in the mid-18th century, accompanied by French Jesuit missionaries. Akwesasne spans the boundaries of Canada and the United States, extending across the St. Lawrence River into New York State, where it is referred to as the St. Regis Reservation.

• Akwesasne
• Kahnawake