GAMESS (US) is a computational chemistry software program that stands for General Atomic and Molecular Electronic Structure System. The original code started on October 1, 1977 as a National Resources for Computations in Chemistry project. In 1981, the code base split into GAMESS (US) and GAMESS (UK) variants, which now differ significantly. GAMESS (US) is maintained by the members of the Gordon research group at Iowa State University.