From Ohio History Central
On February 10, 1808, the Ohio government authorized the creation of Delaware County. The county was originally part of Franklin County. Residents chose to name the county after the Delaware Indian tribe. The county was the birthplace of President Rutherford B. Hayes. It also is home to Ohio Wesleyan University, a school established by Methodists in 1842. Due to the large number of deeply religious people in the county, during the 1830s, 1840s, 1850s, and 1860s, residents played an important role in the Underground Railroad.
Delaware County is located in the central portion of Ohio. The county seat is Delaware, which is the largest population center, with just over twenty-five thousand residents in 2000. This marked a twenty-five percent growth in the town's population since 1990, and the county, itself, experienced a fifty percent growth rate, to a total population of 109,989 people, during this same period. Delaware County is Ohio's fastest growing county, as residents of nearby Franklin County try to escape the busyness of Columbus. An average of 249 people live in each of Delaware County's 442 square miles.