When David Knisely, the founder of New Philadelphia, first arrived in the Tuscarawas Valley on August 27, 1803, he found a sparsely populated, pristine wilderness. Five years later the state legislature approved a bill organizing Tuscarawas County effective March 15, 1808. Shortly thereafter, New Philadelphia was chosen as the county seat, and on April 16, 1808, the first commissioners met at Leininger's tavern. By August, the tavern proved to be an inappropriate location for the county's official business, and the commissioners approved the construction of a two-story, combination jail and county office building on land donated by John Knisely on the northeast corner of the square. By 1818 a new, larger brick courthouse was authorized by the commissioners. This building was occupied in 1825 and served as the courthouse until 1882 when the present structure was approved. Occupied in 1888, the building continues to be the center of the county's business. The beautiful, state-of-the-art annex was dedicated on October 27, 1990.
On February 19, 1803, Ohio Officially became the first state in the federal union to be carved from the Northwest Territory. Five years later, on March 15, 1808, Tuscarawas became the twenty-seventh county to be organized in the new state. Eventually there would be a total of eighty-eight counties. For the next four years, the new county went through seven external boundary changes, as shown in the above maps. Finally, in 1848, it assumed its current and final configuration.