Named after Luther M. Kennett, mayor of St. Louis
The town was briefly called Dunklin Court House in 1845-46 and then named Chilletecaux after a Delaware Indian chief. Around 1849 the State Legislature changed the name to Butler. In 1851, the name was finally changed to Kennett.
| Year | Population | Percent change |
|---|---|---|
| 1900 | 1,509 | -- |
| 1910 | 3,033 | +101.0% |
| 1920 | 3,622 | +19.4% |
| 1930 | 4,128 | +14.0% |
| 1940 | 6,335 | +53.5% |
| 1950 | 8,685 | +37.1% |
| 1960 | 9,098 | +4.8% |
| 1970 | 10,090 | +10.9% |
| 1980 | 10,145 | +0.5% |
| 1990 | 10,941 | +7.8% |
| 2000 | 11,260 | +2.9% |