Franklin County is a county located in the state of Ohio, United States. According to the 2010 census, it has a population of 1,163,414, which is an increase of 8.8% from 1,068,978 in 2000. It is the second largest county in Ohio (after Cuyahoga County) and the 34th largest county in population in the United States. Franklin County is also the largest in the eight-county Columbus, Ohio Metropolitan Statistical Area. Its county seat is Columbus, which is located in the middle of the county. Columbus is the capital and largest city in Ohio, as well as the 15th largest city in the United States, according to the U.S. Census Bureau's 2005 Population Estimates. Columbus makes up about 66.56% of the population of the county, the rest being provided by various suburbs and townships, and Franklin County itself makes up about 9.42% of the state population as of 2000.
Franklin County, particularly Columbus, has been a centerpiece for presidential and congressional politics, most notably the 2000 presidential election, the 2004 presidential election, and the 2006 midterm elections. Franklin County is home to the largest university in the United States, The Ohio State University, which as of fall 2011 has an enrollment of 56,867 students on its main Columbus campus.
The county was established on April 30, 1803, less than two months after Ohio became a state, and was named after Benjamin Franklin. Franklin County originally extended all the way north to Lake Erie before Ohio subdivided further into more counties.