The Symmes Purchase, also known as the Miami Purchase, a section of land in Southwestern Ohio in what is now Hamilton, Butler, and Warren Counties. It was purchased by Judge John Cleves Symmes of New Jersey from the Continental Congress. In the 1780s, Benjamin Stites, a friend of Symmes', was visiting Limestone (now Maysville, Kentucky), and had some of his horses stolen by Indians. He pursued them through the wilderness of southwestern Ohio as far north as Xenia. He was so impressed with the fertility of the country he informed Symmes of its prospects and Symmes gathered a syndicate to buy the land.

The tract is bordered on the south by the Ohio River, on the west by the Great Miami River, and on the east by the Little Miami River. The northern boundary runs through Butler and Warren Counties about twenty-five miles north of the Ohio River. Sections of Todhunter and Garver Roads in Monroe, Monroe Road in Lebanon, and Oregonia Road in Turtlecreek Township run along the boundary.

Unfortunately, the survey conducted by Symmes's men was done poorly, e.g. the surveyors used magnetic north rather than correcting for true north. Further, Symmes sold much land that he did not own, some as far north as Dayton, meaning some early settlers found themselves squatters on the public domain, and some he did own more than once.

The Symmes Purchase survey is the only one in the United States where the ranges run from north to south and the townships from east to west. The section numbering is in accordance with the Land Ordinance of 1785. The survey here also was done to magnetic north rather than true north. Deeds in this area will refer to the Between the Miami Rivers Survey, (M.R.S.).

See also: Ohio lands