Montgomery County, Ohio

Montgomery County
Current Montgomery County Courthouse
Location within the U.S. state of Ohio
Ohio's location within the U.S.
Coordinates: 39°45′N 84°17′W / 39.75°N 84.29°W / 39.75; -84.29
Country United States
State Ohio
FoundedMay 1, 1803
Named afterRichard Montgomery
SeatDayton
Largest cityDayton
Area
  Total
464 sq mi (1,200 km2)
  Land462 sq mi (1,200 km2)
  Water2.8 sq mi (7 km2)  0.6%
Population
 (2020)
  Total
537,309
  Estimate 
(2021)
535,840
  Density1,200/sq mi (450/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional district10th
Websitewww.mcohio.org

Montgomery County is in the southwestern part of the U.S. state of Ohio. At the 2020 census, the population was 537,309, making it the fifth-most populous county in Ohio. The county seat is Dayton. The county was named in honor of Richard Montgomery, an American Revolutionary War general, who was killed in 1775 while attempting to capture Quebec City, Canada. Montgomery County is part of the Dayton, Ohio, Metropolitan Statistical Area.