Châteauguay, city in Châteauguay County, southern Québec, Canada, on the Châteauguay River and Lake St.-Louis. Châteauguay is a residential suburb southwest of Montréal. The city's economy is based mainly on manufacturing and services. Attractions include Saint-Joachim Church, which was built in 1775, and a masonry tower built in the 1680s, which is a remnant of one of the oldest windmills in North America. The Battle of Châteauguay, an important victory for Britain over the United States in the War of 1812, was fought near the city. The battle site is now a national historic site. Châteauguay developed as a center for the agricultural and forestry industries in the region. It grew significantly early in the 20th century. It incorporated as a city in 1912 and merged with the town of Châteauguay-Centre in 1975.
Châteauguay covers a land area of 35.4 sq km (13.7 sq mi). Population 39,833 (1991); 41,423 (1996).
