Montreal Island: Size, Rank, and Geographic Significance

Montreal Island (Île de Montréal) spans 482.13 km² (186.15 sq mi), making it the 32nd largest island in Canada by area—a modest ranking nationally but massive in urban significance.

Dimensions and Shape

• Length: ~50 km (31 mi) southwest-northeast
• Max width: ~16 km (10 mi)
• Perimeter: ~266 km (165 mi) of shoreline
• Shape: Irregular, elongated, deeply indented by bays and river channels

Hydrology: Island Defined by Water

Confluence of three major rivers creates the island:

• St. Lawrence River - south/southeast (main channel)
• Rivière des Prairies - north (separates from Laval)
• Lac des Deux Montagnes - west (Ottawa River widening)

These waterways historically enabled trade, defense, and now recreation.

Urban Concentration

Despite modest physical size, the island hosts:

• 2.0+ million people (2021) - ~5.4% of Canada's population
• 16 municipalities including Montreal (1.76M), Laval (separate island north), Longueuil (south shore)
• Density: ~4,200/km² - 2nd highest in Canada (after Vancouver metro)

Geological Story

Monteregian Hills (Mont Royal, Mont Saint-Bruno, etc.) are Cretaceous intrusions (124-138 Ma) piercing sedimentary plains. Mont Royal (233m) anchors the city. The island itself is largely Champlain Sea deposits (post-glacial, ~10,000 years) over older bedrock.

Comparative Context

• Larger than: Barbados (430 km²), Grenada (344 km²), Malta (316 km²)
• Smaller than: Prince Edward Island (5,660 km²), Newfoundland (108,860 km²), Baffin Island (507,451 km²)
• Similar to: Singapore (728 km² but 5.6M people), Isle of Man (572 km²)

Montreal Island proves that geographic size ≠ urban significance. Its strategic river confluence made it a continental crossroads long before it became Canada's cultural capital.