Posey County is a county in Indiana, United States, at the confluence of the Ohio and Wabash rivers in the state’s southwest corner. It had a population of 25,222 at the 2020 census and covers 419.32 square miles (1,086.0 km2) — 409.57 square miles (1,060.8 km2) of land and 9.75 square miles (25.3 km2) of water — centred near 38°01′N 87°52′W.
Mount Vernon is the county seat, and its postal code is 47620. The county has one city, four incorporated towns, and a scatter of small unincorporated communities, spread across ten civil townships. Posey County is part of the Evansville, Indiana metropolitan area and runs on Central time. Its FIPS code is 18129.
Towns & Villages in Posey County
Posey County has five incorporated places — one city and four towns — plus roughly two dozen unincorporated communities and crossroads. In the table below, “City · seat” marks the county seat, “Town” marks the other incorporated municipalities, and “Unincorp.” marks places with no municipal government of their own.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Mount Vernon | City · seat | Robinson | — | 47620 |
| Cynthiana | Town | Robb | — | 47612 |
| Griffin | Town | Point | — | 47616 |
| New Harmony | Town | Harmony | — | 47631 |
| Poseyville | Town | Marrs | — | 47633 |
| Wadesville | Unincorp. | Black | — | 47638 |
| Blairsville | Unincorp. | Center | — | — |
| Caborn | Unincorp. | Robinson | — | — |
| Erwin | Unincorp. | Bethel | — | — |
| Farmersville | Unincorp. | Lynn | — | — |
| Forest Hill | Unincorp. | Smith | — | — |
| Grafton | Unincorp. | Marrs | — | — |
| Hepburn | Unincorp. | Lynn | — | — |
| Heusler | Unincorp. | Bethel | — | — |
| Hovey | Unincorp. | Bethel | — | — |
| Lippe | Unincorp. | Marrs | — | — |
| Marrs Center | Unincorp. | Marrs | — | — |
| New Baltimore | Unincorp. | Black | — | — |
| Oak Grove | Unincorp. | Robb | — | — |
| Oliver | Unincorp. | Center | — | — |
| Saint Philip | Unincorp. | Smith | — | — |
| Saint Wendel | Unincorp. | Robinson | — | — |
| Savah | Unincorp. | Bethel | — | — |
| Solitude | Unincorp. | Harmony | — | — |
| Springfield | Unincorp. | Robb | — | — |
| Stewartsville | Unincorp. | Robinson | — | — |
| Upton | Unincorp. | Smith | — | — |
| West Franklin | Unincorp. | Point | — | — |
Mount Vernon, the largest place, sits on the Ohio River south of the county’s midpoint and anchors the Ports of Indiana–Mount Vernon river terminal. New Harmony, on the Wabash near the Illinois line, is the smallest incorporated town by area but the best known historically, having twice hosted 19th-century utopian communal societies.
Townships
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Robinson | — | Mount Vernon, Caborn, Saint Wendel, Stewartsville |
| Bethel | — | Erwin, Heusler, Hovey, Savah |
| Black | — | Wadesville, New Baltimore |
| Center | — | Blairsville, Oliver |
| Harmony | — | New Harmony, Solitude |
| Lynn | — | Farmersville, Hepburn |
| Marrs | — | Poseyville, Grafton, Lippe, Marrs Center |
| Point | — | Griffin, West Franklin |
| Robb | — | Cynthiana, Oak Grove, Springfield |
| Smith | — | Forest Hill, Saint Philip, Upton |
Township-level 2020 census counts are not separately published for Posey County’s civil townships, so population figures are omitted rather than estimated.
ZIP Codes
- 47620 — Mount Vernon (also serves Caborn, Saint Wendel, Stewartsville)
- 47638 — Wadesville (also serves New Baltimore)
- 47633 — Poseyville (also serves Grafton, Lippe, Marrs Center)
- 47631 — New Harmony (also serves Solitude)
- 47612 — Cynthiana (also serves Oak Grove, Springfield)
- 47616 — Griffin (also serves West Franklin)
Smaller crossroads such as Blairsville, Erwin, Farmersville, Forest Hill, Hepburn, Heusler, Hovey, Oliver, Saint Philip and Upton share a ZIP code with the nearest post-office town rather than having their own.
Geography
Posey County occupies the extreme southwestern tip of Indiana, at the point where the Wabash River empties into the Ohio. The Ohio River forms the county’s entire southern boundary, and the Wabash forms its western boundary with Illinois. The interior is mostly flat farmland broken by bottomland forest along both rivers, with the Hovey Lake wetland complex in the county’s far south.
Posey County borders Gibson County to the north and Vanderburgh County to the east, both in Indiana; Union County and Henderson County, Kentucky, across the Ohio River to the south; and Gallatin County and White County, Illinois, across the Wabash River to the west. Verified sibling pages: Gibson County, Vanderburgh County, Union County, Kentucky, Henderson County, Kentucky, Gallatin County, Illinois, and White County, Illinois.
Demographics
Posey County’s population was 25,222 at the 2020 census. Mount Vernon is by far the largest community, followed by Poseyville. Median household income in the county runs close to the Indiana median of $69,477, reflecting a mix of industrial and farm income. Density works out to roughly 62 people per square mile of land.
Economy & Local Life
Heavy industry and river shipping anchor the county’s economy. The Ports of Indiana–Mount Vernon complex, the seventh-largest inland port in the country by tonnage, moves grain, coal, steel, and fertilizer along the Ohio River, and a cluster of power and manufacturing plants line the riverfront near Mount Vernon. Away from the river, the county is heavily farmed for corn and soybeans. New Harmony draws visitors year-round as a preserved historic-district town built around its 19th-century communal-society sites and the Atheneum visitor center.
History
Posey County was organized in November 1814 out of Gibson and Warrick counties, and it is named for Thomas Posey, then serving as governor of the Indiana Territory. Mount Vernon was designated the county seat in 1825. New Harmony, founded in 1814 by the Harmony Society and taken over in 1825 by Robert Owen’s utopian Owenite community, gave the county an outsized role in early American social and scientific history — several members of the Owen circle went on to found the U.S. Geological Survey and shape the Smithsonian Institution.
Getting There
Interstate 64 crosses the northern part of the county, and State Roads 62, 65, 66, 68, 69, and 165 connect its towns to Evansville and the river crossings into Kentucky and Illinois.
- Mount Vernon — 15 miles southwest of Evansville
- New Harmony — 25 miles west of Evansville
- Evansville, Indiana — 15 miles northeast of Mount Vernon
- Henderson, Kentucky — 20 miles south of Mount Vernon across the Ohio River
Evansville Regional Airport, roughly 20 miles northeast of Mount Vernon, is the nearest commercial airport.
Frequently Asked Questions
Where is Posey County?
It is in the extreme southwestern corner of Indiana, where the Wabash River meets the Ohio River, part of the Evansville metropolitan area.
What is the population of Posey County?
25,222 people, per the 2020 census.
How big is Posey County?
419.32 square miles (1,086.0 km2), of which 409.57 square miles is land.
What is the county seat of Posey County?
Mount Vernon is the county seat.
How many towns are in Posey County?
One city (Mount Vernon) and four incorporated towns (Cynthiana, Griffin, New Harmony, and Poseyville), plus roughly two dozen unincorporated communities.
What ZIP codes are in Posey County?
47612, 47616, 47620, 47631, 47633, and 47638.
Why is New Harmony historically significant?
It was the site of two 19th-century utopian communal societies, the Harmony Society and Robert Owen’s Owenite community, and remains a preserved historic-district town.
More counties in this state: Towns and villages in Indiana.