Harrison County is located in the Seven Ranges of Ohio, which was designated by Congress in 1787 as the first portion of the wilderness to be settled in the westward expansion. Settlers arrived in the area in the mid 1790s, several years prior to Ohio statehood in 1803.
Harrison County was formed in 1813 by combining portions of Jefferson and Tuscarawas counties. Harrison County contains 15 townships and 10 incorporated villages within its borders. The county's population in the 2010 census was 15,856.