Dearborn County once included an area from Fort Recovery, Ohio Southwest to Madison, Indiana. Which included all or part of Wayne, Franklin, Union, Fayette, Dearborn, Ohio, Rush and Switzerland Counties. This was taken from a report about 1807 census.
The First Courthouse of Dearborn County was one half of a double log cabin belonging to Doctor Jabez Percival, one of the associate judges.
How The Dearborn County Boundaries (Also Known As the "Gore Area" until 1820) Changed.
07 Mar 1803 -- DEARBORN created by Indiana Territory from CLARK. (Ind. Terr., Exec. Journal, 116)
01 Jan 1811 -- DEARBORN lost to creation of FRANKLIN, JEFFERSON, and WAYNE. (Ind. Terr. Laws, 1809-1816, chs. 6, 60/pp. 108-111, 190)
01 Oct 1814 -- DEARBORN gained from JEFFERSON, lost to creation of SWITZERLAND. (Ind. Terr. Laws, 1809-1816, ch. 9/pp. 538-542)
11 Dec 1816 -- DEARBORN became a county in Indiana when the state of Indiana was created from Indiana Territory and small parts of Illinois and Michigan Territories. (U.S. Stat., vol. 3, ch. 57 [1816], secs. 1-2/p. 289 and res. 1 [1816]/p. 399; Van Zandt, 115)
27 Dec 1816 -- DEARBORN lost to creation of RIPLEY; RIPLEY not fully organized, part attached to DEARBORN for administrative and judicial purposes. (Ind. Acts 1816, 1st sess., ch. 45, sec. 10/p. 199)
10 Apr 1818 -- RIPLEY fully organized, detached from DEARBORN. (Ind. Acts 1817, 2d sess., spec., ch. 13/p. 32)
05 Dec 1842 -- DEARBORN boundaries were redefined; mistake in description corrected 13 January 1845 [no change]. (Ind. Rev. Stat. 1843, ch. 2, secs. 2, 26, 28-31, 36-37, 42-44, 61, 67, 77, 80-82, 85-86/pp. 68, 74-81, 84, 86, 88-89)
01 Mar 1844 -- DEARBORN lost to creation of OHIO; OHIO not fully organized, attached to DEARBORN for administrative and judicial purposes. (Ind. Acts 1843, 28th sess., gen., ch. 2, secs. 1, 13/pp. 7, 9)
01 May 1844 -- OHIO fully organized, detached from DEARBORN. (Ind. Acts 1843, 28th sess., gen., ch. 2, sec. 4/p. 7)
07 Jan 1845 -- DEARBORN lost to OHIO. (Ind. Acts 1844, 29th sess., loc., ch. 230, secs. 1-2/p. 225)
13 Jan 1845 -- DEARBORN boundaries were clarified, correcting mistake of 5 December 1842 [no change]. (Ind. Acts 1844, 29th sess., loc., ch. 107/p. 136)