The term “Grammar/Union High School” in Union, South Carolina, refers to a historic educational building located at 401 East Main Street. Constructed in 1909, this two-story brick structure showcases Neo-Classical architecture, featuring a brick parapet, central projecting bay, and a large pedimented portico supported by composite columns.

Originally established as Union High School, it served as the county’s first secondary school, accommodating students from the eighth through eleventh grades. By 1927, due to increasing enrollment, grammar school students were moved into the building, and it was subsequently renamed Main Street Grammar School.

In 1965, the building was acquired by the University of South Carolina Union (USC Union) and rehabilitated to serve as its main campus facility. The structure was added to the National Register of Historic Places on July 20, 1989, and is also a contributing property within the East Main Street–Douglass Heights Historic District.

 Today, the building continues to function as part of USC Union, preserving its historical significance while serving the educational needs of the community.