It is the principal city of the Union Micropolitan Statistical Area (population 28,961 according to 2010 Census), which includes all of Union County and which is further included in the greater Greenville-Spartanburg-Anderson, South Carolina Combined Statistical Area (population 1,266,995 according to the 2010 Census).

Union County's population grew the fastest between 1762 and the start of the Revolutionary War.

Settlers built log cabins and cultivated tobacco, flax, corn and wheat.

According to the United States Census Bureau, the city has a total area of 8.0 square miles (21 km2), all of it land.

[7] As of the 2020 United States census, there were 8,174 people, 3,452 households, and 2,063 families residing in the city.

USC Union was founded in 1965 and is accredited by the Southern Association of Colleges and Schools.

[12] This Carnegie library provides services and resources for both the community and USC Union students.