Founded in 1812, Saint Louis County is one of 114 counties in the state of Missouri. Historically, Saint Louis County was one of the five original counties. The city of Clayton is the county seat. With FIPS code of 189, Saint Louis County has a population of 997,187 and area of 508 square miles (1,316 km2).
List of all cities in Saint Louis County, MO alphabetically
| City/Town | Postal Code | Area Code |
| Bank of America, MO | 63150 | 314/551 |
| 63160 | 314/551 | |
| Courtesy Reply Mail Firms, MO | 63197 | 314/551 |
| Firstar Bank, MO | 63195 | 314/551 |
| Goodfellow Terrace, MO | 63120 | 314/551 |
| IBSSC Acs Asc, MO | 63180 | 314/551 |
| 63182 | 314/551 | |
| Laclede Gas Co, MO | 63171 | 314/551 |
| Louis, MO | 63113 | 314/551 |
| Nestle, MO | 63164 | 314/551 |
| Nordstrom, MO | 63190 | 314/551 |
| Pine Lawn, MO | 63120 | 314/551 |
| Saint Louis, MO | 63101 | 314/551 |
| 63102 | 314/551 | |
| 63103 | 314/551 | |
| 63104 | 314/551 | |
| 63106 | 314/551 | |
| 63107 | 314/551 | |
| 63108 | 314/551 | |
| 63109 | 314/551 | |
| 63110 | 314/551 | |
| 63111 | 314/551 | |
| 63112 | 314/551 | |
| 63113 | 314/551 | |
| 63115 | 314/551 | |
| 63116 | 314/551 | |
| 63118 | 314/551 | |
| 63120 | 314/551 | |
| 63139 | 314/551 | |
| 63147 | 314/551 | |
| 63150 | 314/551 | |
| 63155 | 314/551 | |
| 63156 | 314/551 | |
| 63157 | 314/551 | |
| 63158 | 314/551 | |
| 63160 | 314/551 | |
| 63163 | 314/551 | |
| 63164 | 314/551 | |
| 63166 | 314/551 | |
| 63169 | 314/551 | |
| 63171 | 314/551 | |
| 63177 | 314/551 | |
| 63178 | 314/551 | |
| 63179 | 314/551 | |
| 63180 | 314/551 | |
| 63182 | 314/551 | |
| 63188 | 314/551 | |
| 63190 | 314/551 | |
| 63195 | 314/551 | |
| 63197 | 314/551 | |
| 63199 | 314/551 | |
| US Bank, MO | 63195 | 314/551 |
| USPS Inspection Service, MO | 63199 | 314/551 |
| Wellston, MO | 63112 | 314/551 |