- Location: St. Louis County, Missouri
- Legal status: Home rule city
- Population: 6,871 (Change since 1990: -8.0%)
- Alternate name: St. Johns
- Latitude: 38°42'48" N (+38.7133)
- Longitude: 90°20'35" W (-90.3431)
- Land area: 1.4 square miles
As the crow flies, St. John is...
| Year | Population | Percent change |
|---|
| 1950 | 2,499 | -- |
| 1960 | 7,342 | +193.8% |
| 1970 | 8,960 | +22.0% |
| 1980 | 7,854 | -12.3% |
| 1990 | 7,466 | -4.9% |
| 2000 | 6,871 | -8.0% |