Simpson County is a county in Kentucky, United States, on the Tennessee state line in the south-central part of the state. It had a population of 19,594 at the 2020 census and covers 234 square miles (610 km2) of land, centred near 36°44′N 86°35′W.
Franklin is the county seat, and its postal code is 42134 (a second code, 42135, serves Franklin post office boxes only). The county has one incorporated city and a handful of small unincorporated communities. It sits in the Central time zone.
Towns & Villages in Simpson County
Simpson County has one incorporated city, Franklin, plus a scatter of small unincorporated communities and old crossroads settlements. Population figures below are 2020 census counts where the place is a recognized census entity; unincorporated hamlets are historic place names carried from county records and have no separate census count (marked —).
| Place | Type | Pop. | ZIP |
|---|---|---|---|
| Franklin | City · seat | 10,176 | 42134 |
| Gold City | Unincorp. | — | 42134 |
| Middleton | Unincorp. | — | 42134 |
| Neosheo | Unincorp. | — | 42134 |
| Prices Mill | Unincorp. | — | 42134 |
| Providence | Unincorp. | — | 42134 |
| Salmons | Unincorp. | — | 42134 |
| Black Jack | Unincorp. | — | 42134 |
| Bornes Ford | Unincorp. | — | 42134 |
| Flat Rock | Unincorp. | — | 42134 |
| Geddes | Unincorp. | — | 42134 |
| Hickory Flat | Unincorp. | — | 42134 |
| Highland | Unincorp. | — | 42134 |
| Hillsdale | Unincorp. | — | 42134 |
| Peden Mill | Unincorp. | — | 42134 |
| Schweizer | Unincorp. | — | 42134 |
| Temperance | Unincorp. | — | 42134 |
| Turnertown | Unincorp. | — | 42134 |
The old county list duplicated Black Jack twice; the repeat has been dropped here. Every other named place is retained. Because the entire county shares Franklin’s mail service, all of these places fall under the single 42134 ZIP code.
ZIP Codes
- 42134 — Franklin (covers the entire county, including every unincorporated community listed above)
- 42135 — Franklin (post office box addresses only)
No other community in the county has its own postal designation; all mail is routed through Franklin.
Geography
Simpson County lies in the Pennyroyal Plateau, a gently rolling limestone-karst region of south-central Kentucky known for sinkholes and underground drainage. Drum Creek and its tributaries drain much of the county toward the Barren River system. Land use is mostly farmland and pasture, with Franklin as the only significant built-up area. Row crops, tobacco, and cattle pasture dominate outside town, and the karst terrain means creeks frequently disappear underground before reemerging downstream.
The county borders Warren County to the north, Allen County to the east, Sumner County, Tennessee to the southeast, Robertson County, Tennessee to the southwest, and Logan County to the west.
Demographics
Simpson County’s population was 19,594 at the 2020 census, with Franklin the largest community at 10,176 residents — more than half the county’s total. Median household income in the county runs below the Kentucky median of $61,118, consistent with other rural south-central Kentucky counties. Overall density is about 84 people per square mile, concentrated heavily around Franklin.
Economy & Local Life
Agriculture, light manufacturing, and logistics anchor the county’s economy. Kentucky Downs, a horse-racing track and gaming venue just outside Franklin, is a major regional draw and employer. In December 2025, Kroger announced a $391 million automated grocery distribution center in Franklin expected to create about 430 jobs, part of a broader push of warehouse and distribution investment along the I-65 corridor.
History
Simpson County was formed in 1819 from parts of Allen, Logan, and Warren counties. It is named for Captain John Simpson, a Kentucky militia officer who fought in the Battle of Fallen Timbers during the Northwest Indian War and was killed at the Battle of River Raisin in the War of 1812. Franklin, the county seat, was incorporated the following year, 1820, and named for Benjamin Franklin. The county is also remembered for the January 1948 death of Kentucky Air National Guard Captain Thomas Mantell, who crashed while pursuing an unidentified object near Franklin — one of the earliest widely publicized UFO-related fatalities in U.S. history.
Getting There
Interstate 65 runs north-south through the county past Franklin, with US 31W and KY 100 providing additional routes. The nearest commercial airport is Bowling Green-Warren County Regional Airport, about 20 miles north of Franklin.
- Bowling Green, Kentucky — 20 miles north
- Nashville, Tennessee — 40 miles south
- Scottsville, Kentucky — 20 miles east
- Russellville, Kentucky — 20 miles west
Frequently Asked Questions
Where is Simpson County?
It is in south-central Kentucky, on the Tennessee state line along Interstate 65, between Bowling Green and Nashville.
What is the population of Simpson County?
19,594 people, as of the 2020 census.
How big is Simpson County?
234 square miles (610 km2) of land, plus about 2.3 square miles (6.0 km2) of water.
What is the county seat of Simpson County?
Franklin is the county seat.
How many towns are in Simpson County?
Franklin is the only incorporated city; the rest of the county is made up of small unincorporated communities and rural crossroads.
What ZIP codes are in Simpson County?
42134 (Franklin and the surrounding county) and 42135 (Franklin post office boxes).
Why is Simpson County named that?
It honors Captain John Simpson, a Kentucky militia officer killed at the Battle of River Raisin in 1813.
More counties in this state: Towns and villages in Kentucky.