The South Pole Telescope is a Cosmic Microwave Background instrument that surveys the southern sky for Sunyaev-Zel'dovich effect signatures from clusters of galaxies.  The SPT-SZ and SPT-Pol surveys are complete, and the SPT-3G survey is in progress with a completion date of 2023.  The S-Z signatures of approximately 6000 clusters will be detected in a survey area that covers about 1/10 of the sky, yielding a catalog of galaxy clusters that is redshift-independent and mass-limited at ~ 2 x 10^14 solar masses.  Cluster candidates are followed up with X-ray, visual, infrared, and radio observations for cosmology and cluster physics.