Greenville County is located in the U.S. state of South Carolina. As of the 2020 census, the population was 525,534, making it the most populous county in the state. Its county seat is Greenville. The county is also home to the Greenville County School District, the largest school system in South Carolina.

Donaldson Air Force Base is a former facility of the United States Air Force located south of Greenville, South Carolina. It was founded in 1942 as Greenville Army Air Base; it was deactivated in 1963 and converted into a civilian airport. It is currently an active airfield known as Donaldson Center Airport.