Montgomery County is a county in Ohio, United States, anchored by the city of Dayton on the Great Miami River. It had a population of 537,309 at the 2020 census and covers 464 square miles (1,201 km2), centred near 39°45′N 84°17′W, in the southwest part of the state.
Dayton is the county seat; its postal code is 45402. The county contains 18 incorporated cities, 4 villages, and 9 townships covering the unincorporated remainder. Montgomery County is in the Eastern time zone (UTC−5, UTC−4 during daylight saving) and carries FIPS code 39113.
Towns & Villages in Montgomery County
Montgomery County has 18 incorporated cities and 4 incorporated villages, plus a number of unincorporated communities and mobile-home parks scattered across its nine townships. “CDP” below marks a census-designated place with no city government; “Unincorp.” marks a named community or crossroads with no incorporated status.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Dayton | City · seat | — | 137,644 | 45402 |
| Kettering | City | — | 56,163 | 45429 |
| Huber Heights | City | — | 39,323 | 45424 |
| Centerville | City | — | 25,377 | 45459 |
| Miamisburg | City | — | 21,146 | 45342 |
| Trotwood | City | — | 22,505 | 45426 |
| West Carrollton | City | — | 13,143 | 45449 |
| Vandalia | City | — | 15,246 | 45377 |
| Riverside | City | — | 25,201 | 45431 |
| Englewood | City | — | 13,747 | 45322 |
| Oakwood | City | — | 9,202 | 45419 |
| Moraine | City | — | 6,461 | 45439 |
| Springboro | City | — | — | 45066 |
| Union | City | — | — | 45322 |
| Clayton | City | — | — | 45315 |
| Carlisle | City | — | — | 45005 |
| Brookville | City | — | — | 45309 |
| Germantown | City | — | — | 45327 |
| New Lebanon | Village | — | — | 45345 |
| Farmersville | Village | — | — | 45325 |
| Verona | Village | — | — | 45378 |
| Phillipsburg | Village | — | — | 45354 |
| Shiloh | Unincorp. | Harrison | — | — |
| Northridge | Unincorp. | Harrison | — | — |
| Old North Dayton | Unincorp. | — | — | — |
| Riverdale | Unincorp. | — | — | — |
| Walnut Hills | Unincorp. | — | — | — |
| Shakertown | Unincorp. | Washington | — | — |
| Little York | Unincorp. | Butler | — | — |
| Johnsville | Unincorp. | Perry | — | — |
Some of Montgomery County’s neighborhoods sit inside Dayton’s own city limits rather than as separate communities — East Dayton, North Riverdale, Upper Dayton View, and Five Oaks are Dayton neighborhoods, not independent settlements, and are not counted separately in the table above. Several mobile-home parks carried on older gazetteer lists (Harmony, Ideal, Sunny Acres) are private developments rather than named communities and are omitted here.
Townships
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Washington | — | Centerville area, Shakertown |
| Miami | — | Miamisburg area, West Carrollton area |
| Harrison | — | Shiloh, Northridge |
| Butler | — | Vandalia area, Little York |
| German | — | Germantown area, Miami Villa |
| Jackson | — | Farmersville, New Lebanon |
| Jefferson | — | Brookville area |
| Perry | — | Verona, Johnsville |
| Clay | — | Phillipsburg |
Most of Montgomery County’s population lives inside incorporated cities that have annexed land from their host townships over the decades, which is why 2020 township-level population figures are not separately published for several of the county’s nine townships.
ZIP Codes
- 45402 — Dayton (downtown)
- 45429 — Kettering
- 45459 — Centerville
- 45342 — Miamisburg
- 45424 — Huber Heights
- 45426 — Trotwood
- 45449 — West Carrollton
- 45377 — Vandalia
- 45431 — Riverside
- 45322 — Englewood / Union
- 45419 — Oakwood
- 45439 — Moraine
- 45066 — Springboro
- 45315 — Clayton
- 45005 — Carlisle
- 45309 — Brookville
- 45327 — Germantown
- 45345 — New Lebanon
- 45325 — Farmersville
- 45378 — Verona
- 45354 — Phillipsburg
Dayton itself carries more than a dozen additional ZIP codes for its own neighborhoods (45403–45420 range); the code above marks only its downtown/central post office.
Geography
Montgomery County sits on the Great Miami River, which runs north to south through Dayton and Moraine, joined by the Stillwater and Mad rivers near downtown Dayton and by Wolf Creek and Twin Creek elsewhere in the county. The terrain is gently rolling glacial till plain, largely urbanized in the eastern half around Dayton and more rural and agricultural toward the western townships. Land makes up nearly all of the county’s area, with a small share of water in its rivers and reservoirs.
Montgomery County borders Miami County to the north, Clark County to the northeast, Greene County to the east, Warren County to the southeast, Butler County to the south, Preble County to the southwest, and Darke County to the northwest.
Demographics
Montgomery County had 537,309 residents at the 2020 census, the fifth-most populous county in Ohio. Dayton is by far the largest community, followed by Kettering; together the two make up more than a third of the county’s population. Median household income in the county runs below the Ohio median of $67,769, reflecting Dayton’s legacy manufacturing-era decline, though several southern-suburb communities such as Centerville and Oakwood post household incomes well above the state figure. Population density is roughly 1,160 people per square mile, among the highest of any Ohio county outside the Columbus and Cleveland metros.
Economy & Local Life
Montgomery County’s economy centers on health care, aerospace/defense, and education. Wright-Patterson Air Force Base straddles the Montgomery–Greene county line and is one of the region’s largest employers, alongside Premier Health and Kettering Health, the University of Dayton, and Sinclair Community College. Dayton was historically a major manufacturing center — birthplace of the cash register (NCR) and home to major auto-parts plants — and the region still markets itself as the “Birthplace of Aviation” after the Wright brothers, who lived and worked in Dayton. The Dayton Air Show and the National Museum of the United States Air Force, the world’s largest military aviation museum, draw visitors from across the region each year.
History
Montgomery County was organized on May 1, 1803, the same year Ohio became a state, and was named for Richard Montgomery, a Continental Army general killed in the 1775 assault on Quebec City during the American Revolutionary War. Dayton, platted in 1796 at the confluence of the Great Miami and Mad rivers, became the county seat. The Great Dayton Flood of 1913, which killed hundreds and inundated much of downtown, led directly to the creation of the Miami Conservancy District, one of the country’s earliest regional flood-control systems, whose dams and levees still protect the county today.
Getting There
Interstates 70, 75, and 675 all cross Montgomery County, along with US Routes 35 and 40 and several state routes, making Dayton one of the more highway-connected mid-sized cities in the Midwest.
- Cincinnati — 50 miles south
- Columbus — 70 miles east
- Indianapolis — 100 miles west
- Springfield — 25 miles northeast
Dayton International Airport, in the northern part of the county, offers commercial passenger service; Wright-Patterson Air Force Base, on the Montgomery-Greene line, is a military installation, not a commercial airport.
Frequently Asked Questions
Where is Montgomery County, Ohio?
It is in southwest Ohio, centered on Dayton at the confluence of the Great Miami, Mad, and Stillwater rivers.
What is the population of Montgomery County?
537,309 people at the 2020 census, making it Ohio’s fifth-most populous county.
How big is Montgomery County?
464 square miles (1,201 km2), of which about 462 square miles is land.
What is the county seat of Montgomery County?
Dayton is the county seat.
How many towns and cities are in Montgomery County?
18 incorporated cities and 4 incorporated villages, plus unincorporated communities across nine townships.
What ZIP codes are in Montgomery County?
Dayton’s central ZIP is 45402; suburbs range from 45005 (Carlisle) to 45459 (Centerville) — see the full list above.
Why is it called Montgomery County?
It was named for Richard Montgomery, a Revolutionary War general killed at the 1775 Battle of Quebec.
More counties in this state: Towns and villages in Ohio.