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is the largest city in Jefferson County, Missouri, United States. The population was estimated at 20,413 in 2005.
According to the United States Census Bureau, the city has a total area of 11.6 square miles (30.0 km²), of which, 11.2 square miles (29.1 km²) of it is land and 0.3 square miles (0.9 km²) of it (2.85%) is water.