Chesterfield is a city in St. Louis County, Missouri, United States, and a western suburb of St. Louis. As of the 2010 census, the population was 47,484, making it the state’s fourteenth-largest city. The broader valley of Chesterfield was originally referred to as “Gumbo Flats”, derived from its soil, which though very rich and silty, became like a gumbo when wet. Chesterfield is located approximately 25 miles (40 km) west of St. Louis. According to the United States Census Bureau, the city has a total area of 33.52 square miles (86.82 km2), of which 31.78 square miles (82.31 km2) is land and 1.74 square miles (4.51 km2) is water.Portions of Chesterfield are located in the floodplain of the Missouri River, now known as Chesterfield Valley, formerly as Gumbo Flats.
This area was submerged during the Great Flood of 1993; higher levees built since then have led to extensive commercial development in the valley. Chesterfield Valley is the location of Spirit of St. Louis Airport, used for corporate aviation, as well as the longest outdoor strip mall in America. According to the 2007–2011 American Community Survey estimate, the median income for a household in the city was $95,006, and the median income for a family was $88,568. Males had a median income of $94,322 versus $54,934 for females. The per capita income for the city was $51,725. About 1.7% of families and 4.0% of the population were below the poverty line, including 1.7% of those under age 18 and 3.3% of those age 65 or over.
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