Fairfield County was erected and organized December 9, 1800. At that time it was part of the Northwest Territory and remained part of it until March of 1803 when Ohio became a state. In January 1801, Fairfield County was divided into 3 townships: Hocking, Richland, and Clearcreek. Prior to 1805, Walnut Township was part of Richland Township and in 1805 became part of Pleasant Township when that township was erected. In 1807 or 1808, Walnut Township was erected from the northern part of Pleasant Township. Its name came from Walnut Creek.
Walnut Township is officially known as Township 16 of Range 18 and the northern part of the township contains two rows of sections of Township 17 of Range 18, a part of the Refugee Tract. This tract was set apart by Congress in 1798 to certain persons who left the provinces of Canada and Nova Scotia to aid the cause of freedom in the Revolutionary War.
The first road in Walnut Township was built in 1803 and was called the Lancaster and Newark (New Ark) Pike. This later became the Lancaster-New Salem Road although some still call it the Pleasantville Road. It now is known as Ohio Route 188 or Lancaster-Thornville Road.
William Murphy from Virginia was probably the first settler in Walnut Township in 1800.
Daniel Mauger and Ettie Mauger laid out Roby in 1806. It was located in the southern part of the northwest quarter of section 22 in the Refugee Tract, but apparently was never settled.
New Salem, located halfway between Lancaster and Newark, was laid out December 12, 1832 by Abraham Hashbarger /Harshbarger and David Swazey/Swayze. It may have been named after the town of Salem, Massachusetts.
The Village of Thurston, originally called Hitedale (1849) was laid out as Bush City in 1881 by George Bush, and a year later became Hadley Junction (as called by railroad officials). In 1913 the village officially became Thurston, named for a well-liked Methodist minister.