Formed 16 Jan 1807, 407 square miles
Parent county: Montgomery
Evolution of county from date of formation until it assumed its final form
1 Mar 1807: Erected and organized
3 Jan 1809: Darke attached until organization
7 Jan 1812: Part of Montgomery attached
1 Mar 1817: Diminished by organization of Darke
1 Apr 1819: Diminished by formation of Shelby
1 Apr 1820: Any rights remaining in Indian Lands ceased by formation of counties therein
Miami County's town of Staunton was the county seat in 1807. The following year Troy became the county seat.
Federal Population schedules extant from 1820-1940. (1890 missing)
1820 Manufacturers; 1850 Agricultural; 1850 Industry; 1850 Mortality; 1860 Agricultural; 1860 Mortality; 1880 Agricultural; 1880 Industry
Bethel, Brown, Concord, Elizabeth, Lost Creek, Monroe, Newberry, Newton, Springcreek, Staunton, Union, and Washington.
Jana Broglin, CG, OGSF