is a census-designated place (CDP) in St. Louis County, Missouri, United States. The population was 17,215 at the 2000 census. Lemay was named after Francois Lemai, who operated the ferry across the Meramec River in the early nineteenth century. A casino will be built here and be operational, along with shops and other avenues in St. Louis city proper, by 2010 or 2011. The casino will be owned by Pinnacle Entertainment, which also owns the Lumiere Place Casino and the ailing President Casino Laclede's Landing in St. Louis.
According to the United States Census Bureau, the CDP has a total area of 4.5 square miles (11.7 km²), of which, 4.3 square miles (11.3 km²) of it is land and 0.2 square miles (0.5 km²) of it (4.19%) is water.