In 2015, Statistics Canada identified Montreal's Census Metropolitan Area (CMA) as 4,258.31 square kilometres (1,644.14 sq mi) with a population of 4,027,100,[5] almost half that of the province.

A smaller area of 3,838 square kilometres (1,482 sq mi) is governed by the Montreal Metropolitan Community (MMC; French: Communauté métropolitaine de Montréal, CMM).

Due to their proximity to Montreal's downtown core, some additional suburbs on the South Shore (Brossard, Saint-Lambert, and Boucherville) are usually included in the inner ring, despite their location on the mainland.

Established in June 2007, Exo's commuter rail system has six lines linking the downtown core with communities as far west as Hudson, as Far south as Mont-Saint-Hilaire, as far east as Mascouche, and as far north as Saint-Jérôme.

Along with Exo, a sister agency, the Autorité régionale de transport métropolitain (ARTM) plans, integrates, and coordinates public transport across Greater Montreal, including the Island of Montreal, Laval (Île Jésus), and communities along both the north shore of the Rivière des Mille-Îles and the south shore of the Saint Lawrence River.