First three digits · Kentucky
ZIP Codes Starting with
33 ZIP codes start with 421, sorted at the Nashville, TN (SCF 370) sectional center (USPS labeling list L005, effective October 1, 2026) in Kentucky: 28 residential ZIP codes across 7 counties and 5 PO Box or single-organization codes (Census 2020 ZCTAs and GeoNames postal codes, October 2026).
What do the digits 421 mean?
The first digit, 4, is one of ten national areas (Indiana, Kentucky, Michigan and Ohio). The first three, 421, route mail to a sectional center: USPS labeling list L005 (effective October 1, 2026) sends letters for 421 to the Nashville, TN (SCF 370) facility. The last two digits pick the delivery area. By residents, the largest town names among the 421 ZIP codes are Bowling Green, Glasgow, Franklin, Scottsville, Tompkinsville and Edmonton.
The same facility sorts 7 prefixes, 326 ZIP codes in all: 370, 371, 372, 384, 385, 421, 422.
Where are the 421 ZIP codes?
Source: U.S. Census Bureau, 2020 ZCTA cartographic boundaries; ACS 2020-2024 5-year estimates (B19013).
All ZIP codes starting with 421
| County | ||||||
|---|---|---|---|---|---|---|
| 42101 | Bowling Green | Warren County | 65,421 | 233 | $48k | $207k |
| 42102 | Bowling Green | Warren County | PO Box or unique | – | – | – |
| 42103 | Bowling Green | Warren County | 21,911 | 311 | $88k | $331k |
| 42104 | Bowling Green | Warren County | 42,076 | 725 | $75k | $306k |
| 42120 | Adolphus | Allen County | 2,745 | 63 | $65k | $179k |
| 42122 | Alvaton | Warren County | 5,513 | 146 | $114k | $297k |
| 42123 | Austin | Barren County | 1,149 | 52 | $61k | – |
| 42124 | Beaumont | Metcalfe County | 28 | 14 | – | – |
| 42127 | Cave City | Barren County | 7,030 | 78 | $43k | $164k |
| 42128 | Drake | Warren County | PO Box or unique | – | – | – |
| 42129 | Edmonton | Metcalfe County | 7,302 | 38 | $54k | $111k |
| 42130 | Eighty Eight | Barren County | 124 | 40 | – | $222k |
| 42131 | Etoile | Barren County | 72 | 15 | – | – |
| 42133 | Fountain Run | Monroe County | 1,456 | 19 | $62k | $164k |
| 42134 | Franklin | Simpson County | 19,380 | 91 | $59k | $227k |
| 42135 | Franklin | Simpson County | PO Box or unique | – | – | – |
| 42140 | Gamaliel | Monroe County | 1,367 | 35 | $47k | $92k |
| 42141 | Glasgow | Barren County | 31,506 | 117 | $53k | $185k |
| 42142 | Glasgow | Barren County | PO Box or unique | – | – | – |
| 42151 | Hestand | Monroe County | 201 | 7 | $108k | $165k |
| 42152 | Hiseville | Barren County | PO Box or unique | – | – | – |
| 42153 | Holland | Allen County | 18 | 4 | – | – |
| 42154 | Knob Lick | Metcalfe County | 629 | 26 | $58k | $156k |
| 42156 | Lucas | Barren County | 235 | 31 | $98k | $212k |
| 42157 | Mount Hermon | Monroe County | 507 | 27 | $101k | $175k |
| 42159 | Oakland | Warren County | 1,699 | 54 | $67k | $264k |
| 42160 | Park City | Edmonson County | 2,822 | 44 | $49k | $157k |
| 42163 | Rocky Hill | Edmonson County | 48 | 58 | – | – |
| 42164 | Scottsville | Allen County | 17,673 | 68 | $60k | $197k |
| 42166 | Summer Shade | Metcalfe County | 2,691 | 38 | $50k | $116k |
| 42167 | Tompkinsville | Monroe County | 8,172 | 40 | $49k | $114k |
| 42170 | Woodburn | Warren County | 1,938 | 63 | $96k | $292k |
| 42171 | Smiths Grove | Warren County | 6,723 | 65 | $70k | $188k |
Source: U.S. Census Bureau, ACS 2020-2024 5-year estimates; GeoNames postal codes (CC BY 4.0) for codes without a residential area.