College a cappella pretty much started at Yale in 1909 with the Whiffenpoofs, a Glee Club spin-off quartet that sang regularly at Mory's Temple Bar, a campus restaurant. Now, a cappella singing has exploded, spreading to campuses all over the U.S. and abroad. Read about how this movement has taken off.
A chorus by its very nature is a collaboration - singers, instrumentalists, music directors, front-office staff—all, according to Webster, performing work or labor together, especially literary (read artistic) pursuits." So it comes as no surprise that choruses would extend that collaborative spirit beyond their own organizations.
American Choral Review 45.1