The Symmes Purchase, often called the Miami Purchase, is located in the southwestern corner of the state. It begins at the Ohio River and runs approximately 24 miles northward - between the Great Miami and Little Miami Rivers. The total land area is 311,682 acres including reserves.

John Cleves Symmes and his associates originally contracted for one million acres from the United States Board of Treasury in 1788. In 1792, however, Congress modified this contract, with Symmes’ consent, because Congress did not want Symmes’ tract to interfere with the boundary line established by the Treaty of Fort Harmar.

On September 13, 1794, President George Washington signed the US Patent (Deed) conveying to Symmes 248,250 acres plus a surveying township (23,040 acres), in trust, for an academy. The patent reserved: Fort Washington (15 acres), one square mile near the mouth of the Great Miami; and in each township the following sections: section 16 for schools, section 29 for religion, section 8, 11, and 26 for Congress’s future use. Symmes paid $70,455 in public securities for 105,683 acres and used military bounty land warrants, totaling 95,250 acres, to acquire the remaining 142,857 acres. Because Congress allowed one-third of a dollar off for Bad Lands and incidental charges, Symmes actually paid two-thirds of a dollar per acre.

John Cleves Symmes conveyed the entire 3rd range of township, in trust, to Jonathan Dayton. Symmes did this because Dayton had acquired military bounty warrants from soldiers who desired to settle in the Western County, but could not afford a cash payment. The entire 3rd range is often called the Military Range in the records of Butler and Warren Counties.

Symmes sold land beyond the lands eventually covered by his patent. Technically, these settlers were squatters on unsurveyed federal land. To correct this situation, Congress passed relief acts on March 2, 1799 and March 3, 1801, which gave these settlers the first right to buy this land from the federal government. This was the first time the right of pre-emption was granted by Congress. Later, in 1841, Congress passed a general pre-emption act, which led to fraud and settlement before land could be surveyed.

Symmes Purchase was privately surveyed. It is the only original land surveyed in the United States which has ranges running south to north, fractional ranges, and townships running west to east. Section numbering is according to the land ordinance of May 20, 1785. The federal surveys, above the Symmes Purchase, continued Symmes’ unique and unorthodox numbering of ranges and townships so the “between the Miami Rivers survey” would be consistent.