From Ohio History Central
On December 17, 1817, the Ohio government authorized the creation of Brown County. The county was originally parts of Adams and Clermont Counties. Brown County was named for General Jacob Brown, an American hero from the War of 1812. County residents, including John Rankin, played a major role in the abolitionist movement and Underground Railroad during the 1830s, 1840s, 1850s, and the 1860s. President Ulysses S. Grant also resided in Brown County during his youth. The Ohio Historical Society maintains the Rankin House, Grant Boyhood Home and Grant Schoolhouse as historic sites in Brown County.
Brown County is located in southwestern Ohio, and its southern border resides upon the Ohio River. Brown County's 492 square miles are overwhelmingly rural, with just one-tenth of one percent of the county qualifying as urban area. The largest community in the county is Georgetown, the county seat, which had a population of 3,691 people in 2000. Despite the small urban population, unlike most rural Ohio counties, Brown County experienced tremendous growth between 1990 and 2000. Between 1995 and 2000, approximately twelve thousand people moved to Brown County, increasing the county's population to 42,285 residents.