| Locality | Postal Code |
|---|---|
| Adamsville, Mercer | 16110 |
| Carlton, Mercer | 16311 |
| Clark, Mercer | 16113 |
| Clarks Mills, Mercer | 16114 |
| Delaware, Mercer | 16154 |
| Farrell, Mercer | 16121 |
| Fredonia, Mercer | 16124 |
| Greenville, Mercer | 16125 |
| Grove City, Mercer | 16127 |
| Hadley, Mercer | 16130 |
| Hermitage, Mercer | 16148 |
| Jackson Center, Mercer | 16133 |
| Jamestown, Mercer | 16134 |
| Mercer, Mercer | 16137 |
| Pulaski, Mercer | 16143 |
| Sandy Lake, Mercer | 16145 |
| Sharon, Mercer | 16146 |
| Sharpsville, Mercer | 16150 |
| Sheakleyville, Mercer | 16151 |
| Shenango, Mercer | 16125 |
| South Pymatuning, Mercer | 16154 |
| Stoneboro, Mercer | 16153 |
| Transfer, Mercer | 16154 |
| Volant, Mercer | 16156 |
| West Middlesex, Mercer | 16159 |
| Westford, Mercer | 16134 |