The new town was named after Sir Philip Sidney, an English patriot, writer and member of parliament. The first plat of Sidney, Ohio, was filed on February 24, 1820, and with the county recorder on April 18, 1820.

David Henry hired Benjamin Cox, a surveyor, to lay out the town in 113 lots. Responsible for selling the lots, Henry then gave a 30 day notice of a public auction for these lots in 6 public places throughout the county as well as newspapers such as the Dayton Gazette. As noted in documents found from the period, early spellings of Sidney did include variations such as ‘Sydney". As a matter of fact, in the first book for recording deeds, the plat of Sidney was spelled ‘Sydney’.

The original boundaries were from North Lane to South Lane, (now Water St.), and from the Miami River to West Lane (now West Ave.). Each of the 113 lots measured 5 by 10 rods. The principal streets were six rods and the alleys one rod in width. (A rod is 16 1/2 feet). The streets of the original plat were considered to be uncommonly wide for their time but are today more than adequate enough to meet modern traffic needs.

Lot 113, in the rear of the Presbyterian Church, for which Lot 109 was granted, was set aside as a graveyard; Lot 101, at the corner of West Ave. and South St., was for religious societies, and the east half of Lot 105 was devoted to school purposes. Central school sets upon this lot today.