is a county located in the U.S. state of Missouri. As of the 2010 census, the population was 35,571. Its county seat is Lebanon. The county was organized February 24, 1849, and was named after Pierre Laclède, founder of St. Louis.
According to the U.S. Census Bureau, the county has a total area of 768 square miles (1,990 km2), of which 765 square miles (1,980 km2) is land and 3.3 square miles (8.5 km2) (0.4%) is water.