Middleburg is an unincorporated area and census-designated place (CDP) within Clay County in the U.S. state of Florida, located southwest of downtown Jacksonville and northwest of Green Cove Springs, the county seat of Clay County. As of the 2020 census,the population of Middleburg was 12,881. It is home to Middleburg High School and to the Middleburg Historic District. Geography Middleburg is located northwest of the center of Clay County at (30.050783, -81.902013). Florida State Road Blanding Boulevard leads northeast to the Orange Park area and southwest to Keystone Heights. According to the United States Census Bureau, the Middleburg CDP has a total area of , all land. Demographics As of the census of 2010, there were 13,008 people living in 4,891 housing units within the CDP. Between the 2000 and 2010 census, Middleburg realized a population increase of 2,670 individuals. The racial makeup of the CDP was 92.9% White, 3.1% African American, 0.6% Native American, 0.7% Asian, 0.0% Pacific Islander, 0.9% from other races, and 1.8% from two or more races. Hispanic or Latino of any race were 4.1% of the population. In the CDP, the population was spread out, with 24.87% under the age of 18, 75.13% age of 18 or over, and 10.36% age of 65 or over. The population is 49.7% female and 50.3% male. History Early settlement First settled as a village in the early decades of the nineteenth century, Asa Clark ran the first ferry on Black Creek until 1828, leading to the settlement being called Clark's Ferry. Between 1824 and 1827, the Federal Military Road was constructed, running south from Colerain, Georgia to Tampa Bay. The Federal Military Road passed through Clark's Ferry along the route of present-day Main Street, resulting in increased traffic through the community and providing a postal route. Blakey (1976) wrote of a settlement called Whitesville which existed approximately near the intersection of present-day Florida State Road 21 and County Road 218, and which grew large enough to warrant its own United States Post Office, established on February 19, 1828. That same year, Isaac Boring founded the Black Creek Methodist Church, although the frontier Methodist society met in their own homes until the Methodist United Church was built in 1847. John Hanson took ownership of Clark's ferry from 1828 through 1833, whereafter he sold to Samuel and Charlotte Garey, resulting in the area coming to be known as Garey's Ferry.