A student center is a type of building found on university campuses. In the United States, such a building may be called a student union, student commons, union or student center. The term "student union" refers most often in the United States to a building, while in other nations a "students' union" is the student government. Nevertheless, the Association of College Unions International (largely US-based) has several hundred campus organizational members in the US; there is no sharp dichotomy in interpretation of union in this context. The US usage in reference to a location is simply a shortened form of student union building.
The first student union built at a public university in the United States was the Ohio Union (1910) at the Ohio State University. The largest student union is at Oklahoma State University, Stillwater, Oklahoma.
The first student union in America was Houston Hall, at the University of Pennsylvania, which opened January 2, 1896 and remains in operation to this day. The first Ohio Union at Ohio State University was Enarson Hall. The building opened in 1911 and was the first student union to be built at a state university and the fourth of its kind in the United States.Oklahoma State University's student center opened in 1950. Subsequent additions, and renovations in 2010, have made the building one of the largest student activity centers in the world at 611,000 sq ft (56,800 m2).
Some student centers carry unique origins and historical significance with some on the National Register of Historic Places. The William Pitt Union was originally constructed in 1898 as a hotel and was converted into a student center in 1956. Some student activity centers on the NRHP include O'Hara Student Center (University of Pittsburgh), McKenny Hall (Eastern Michigan University), and the Tivoli Student Union. The Tivoli Student Union was originally home to the Trevoli Brewing Company but since has been converted to serve several institutions in Denver, Colorado.