Anticosti Island, an island in the Gulf of St. Lawrence, Province of Quebec, Canada. It is 137 miles (220 km) long, northeast-southwest, and up to 33 miles (53 km) wide. The area is 3,043 square miles (7,881 km2). Lumbering is the chief industry—the island is owned by a paper-manufacturing corporation. Port Menier, near the western tip, is the island's main settlement.
Anticosti Island was discovered in 1534 by Jacques Cartier of France. In 1680 it was granted to the explorer Louis Joliet; his descendants held it until 1763, when it was annexed to Newfoundland. Anticosti was made part of Quebec in 1774, The island has been privately owned since 1895.