Durham County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 324,833, making it the sixth-most populous county in North Carolina. Its county seat is Durham, which is the only incorporated municipality predominantly in the county, though very small portions of cities and towns mostly in neighboring counties also extend into Durham County. The central and southern parts of Durham County are highly urban, consisting of the city as well as several unincorporated suburbs. Southeastern Durham County is dominated by the Research Triangle Park, most of which is in Durham County. The northern third of Durham County is rural in nature.

Durham is a city in the U.S. state of North Carolina and the county seat of Durham County. Small portions of the city limits extend into Orange County and Wake County. With a population of 283,506 in the 2020 census, Durham is the 4th-most populous city in North Carolina, and the 71st-most populous city in the United States. The city is located in the east-central part of the Piedmont region along the Eno River. Durham is the core of the four-county Durham-Chapel Hill, NC Metropolitan Statistical Area, which had an estimated population of 608,879 in 2023. The Office of Management and Budget also includes Durham as a part of the Raleigh-Durham-Cary, NC Combined Statistical Area, commonly known as the Research Triangle, which had an estimated population of 2,368,947 in 2023.