27271 is a ZIP code located in Johnston County, North Carolina. It includes the city of Smithfield, most of the town of Micro, and the unincorporated area known as Cleveland. The area has a population of around 17,500 people and is the county seat of Johnston County. It is a predominantly rural area with a few small businesses, two elementary schools, two middle schools, and a high school. There is also a community college, Johnston Community College, located in Smithfield. Johnston County Airport is located within the 27271 ZIP code.