Most of its land area is taken up by its county seat, Columbus,[4] the state capital and most populous city in Ohio.

The county was established on April 30, 1803, less than two months after Ohio became a state, and was named after Benjamin Franklin.

Columbus was chosen as the site for the new capital because of its central location within the state and access by way of major transportation routes (primarily rivers) at that time.

The legislature chose it as Ohio's capital over a number of other competitors, including Franklinton, Dublin, Worthington, and Delaware.

[8][full citation needed] On August 30, 1802, James Kilbourne and Nathaniel Little arrived at Colonel Thomas Worthington's home in Chillicothe.

[9][full citation needed] On October 5, 1802, the Scioto Company met again in Granby and decided not to purchase the lands along the Scioto River on the Pickaway Plains, but rather to buy land 30 miles (48 km) farther north from Jonas Stanbery and his partner, an American Revolutionary War general, Jonathan Dayton.

[10][full citation needed] This land was part of the United States Military District surveyed by Israel Ludlow in 1797 and divided into townships 5 miles (8.0 km) square.

The city was originally designed as the state's new capital, preparing itself for its role in Ohio's political, economic, and social life.

In the years between the first ground-breaking and the actual movement of the capital in 1816, Columbus and Franklin County grew significantly.

By 1813, workers had built a penitentiary, and by the following year, residents had established the first church, school, and newspaper in Columbus.

Columbus and Franklin County grew quickly in population, with the city having 700 people by 1815.

[12] The county is located in the Till Plains and the Appalachian Plateau land regions.

From 1996 to 2004, Democratic nominees carried the county by single digit margins, but it swung significantly in favor of Barack Obama in 2008.