The Tri-Cities is the region comprising the cities of Kingsport, Johnson City, and Bristol and the surrounding smaller towns and communities in Northeast Tennessee and Southwest Virginia. All three cities are located in Northeast Tennessee, while Bristol has a twin city of the same name in Virginia. The Tri-Cities region was formerly a single Metropolitan Statistical Area (MSA); due to the U.S. Census Bureau's revised definitions of urban areas in the early 2000s, it is now a Combined Statistical Area (CSA) with two metropolitan components: Johnson City and Kingsport-Bristol (TN)-Bristol (VA).[1] As of the 2000 Census, the CSA had a population of 480,091 (though a July 1, 2008 estimate placed the population at 500,538).

Johnson City is a city in Washington, Carter, and Sullivan counties in the U.S. state of Tennessee, mostly in Washington County. As of the 2020 United States census, the population was 71,046, making it the eighth largest city in Tennessee. Johnson City is the principal city of the Johnson City Metropolitan Statistical Area, which covers Carter, Unicoi, and Washington counties and had a combined population of 200,966 as of 2013. The MSA is also a component of the Johnson City–Kingsport–Bristol, Tennessee–Virginia Combined Statistical Area – commonly known as the "Tri-Cities" region. This CSA is the fifth-largest in Tennessee with an estimated 500,530 residents.

Kingsport is a city in Sullivan and Hawkins counties in the U.S. state of Tennessee; most of the city is in Sullivan County and the city is the largest in both counties, but is the county seat of neither. As of the 2010 census the population was 48,205; as of 2019 the estimated population was 54,127.Kingsport is the largest city in the Kingsport–Bristol–Bristol, TN–VA, Metropolitan Statistical Area (MSA), which had a population of 309,544 as of 2010. The MSA is a component of the Johnson City–Kingsport–Bristol, TN–VA, Combined Statistical Area—commonly known as the "Tri-Cities" region. Census data from 2006–2008 for the Tri-Cities Combined Statistical Area estimates a population of 496,454. Kingsport is commonly included in what is known as the Mountain Empire, which spans a portion of southwest Virginia and the mountainous counties in northeastern Tennessee. The name "Kingsport" is a simplification of "King's Port", originally referring to the area on the Holston River known as King's Boat Yard, the head of navigation for the Tennessee Valley.

Greeneville is a town in and the county seat of Greene County, Tennessee, United States. The population as of the 2010 census was 15,062. The town was named in honor of Revolutionary War hero Nathanael Greene, and it is the second oldest town in Tennessee. It is the only town with this spelling in the United States, although there are numerous U.S. towns named Greenville. The town was the capital of the short-lived State of Franklin in the 18th-century history of East Tennessee.Greeneville is known as the town where United States President Andrew Johnson began his political career when elected from his trade as a tailor. He and his family lived there most of his adult years. It was an area of strong abolitionist and Unionist views and yeoman farmers, an environment which influenced Johnson's outlook.The Greeneville Historic District was established in 1974.The U.S. Navy Los Angeles-class submarine USS Greeneville was named in honor of the town.Greeneville is part of the Johnson City-Kingsport- Bristol TN-VA Combined Statistical Area – commonly known as the "Tri-Cities" region.