The Northwest Territory was formed in 1781. The Greenville Treaty was signed in 1795. Its western border was a line beginning at the mouth of the Kentucky River running northeast to Ft. Recovery, Ohio. This line is the eastern boundary of Ripley County. A triangular parcel of land with its southern border on the Ohio River, the Greenville Treaty line on the west and the present Indiana-Ohio line on the east, formed what was known as the "Gore" on the early maps.
During 1798-99, Benjamin Chambers and Stephen Ludlow made surveys as far north as Olean for Ross Township, Switzerland County, following an old Indian trail. Then in 1807, Stephen Ludlow along with Jon Brownson and Emmanuel Voretrees again surveyed this area.
In 1816 the State of Indiana proposed organization for a new county. The boundaries were thus described: All that part of Jefferson County lying north of the line dividing Townships 5 and 6 North and East of the line beginning at the Southeast comer of Section 31, township 6, North Range 10 East, thence North with the sectional line to the Indiana boundary. Also all that part of Dearborn County West of the old boundary line.
The boundaries of Ripley County as it was later named, were thus laid out in the law forming Jennings County, with the provisions that all that part of Ripley County, which was formerly Dearborn County, remain attached to Dearborn County until Ripley County could be organized. Alteration by statute attaching part of Switzerland County to that of Ripley on Mar. 1, 1822. The new county was named for General Eleazer Wheelock Ripley, a hero of the War of 1812.
January 7 1818, by an act of the General Assemb1y, John DePauw from Washington County, Charles Beggs of Franklin County, and W.H. Eads of Jennings County were appointed to select a site for the new County seat. They were given $3.00 a day for this task They settled on a hundred acre tract in Section 12 Township 7 Range 11 East. John PAUL, of Madison, Jefferson County, IN donated the land. John Paul laid out several towns and was a land speculator.
In May, 1818, the Commissioners divided the new county into three townships. Graham, Laughery and Perry became the oldest townships. A Circuit Court was held at the residence of Benjamin Brown near the present town of New Marion, on July 20, 1618. Conrad Overturf was appointed Clerk and John Richey the first judge.
The county was divided into five townships in November, 1819 namely, Ripley, Hogan, Graham, Perry and Laughery. [Ross, a short-lived fractional township previously forming the 'horn' of northwestern-most neighboring Switzerland County was transferred on March 1, 1822* to Ripley County, afterwards being incorporated into and becoming the southeastern-most corner of Brown Township. * G. Pence & N. C. Armstrong (1933: 768), citing, "Laws of Indiana, 1821-22," p. 127: dated 31 Dec 1821; effective 1 Mar 1822.] Then in 1823 another division was made. Eight townships were named, Jackson, Shelby, Delaware, Franklin, Johnson, Brown, Henry and Washington. Again on June 13, 1858 the present day town-ships were named; Jackson, Otter Creek, Shelby, Center, Laughery, Delaware, Johnson, Brown, Adorns, Franklin and Washington. On September 22, 1819 the county seat was laid out by John Richey.
Napoleon was platted 1820, and was the second town. It was centrally located as roads came through from the north, south, east and west. Other towns soon followed. Cross Plains, 1825; New Marion, 1832 (had to change name as Marion already had a post office); Milan, 1836; Otter Village, 1837; Pennsylvaniaburg, 1837; Ballstown, 1846; Friendship (Hart's Mill), 1850; Batesville, 1852; Holton, 1854; Brooklyn, adjacent to South Milan, just before South Milan, 1854; Spades, 1855; Dabney (Poston), 1855; Sunman and Osgood, 1856; Morris and Olean, 1858; Pierceville, 1860; Delaware, 1869. Any community where a store was in existence could get the customers to sign a petition asking for a post office and one would be established. Included were Tanglewood, Elrod, Correct, Kingwood, Locksprings and many, many others. The population in 1870 was 17,573 native born and 3,404 foreign born.