The Department of Energy (DOE) has recently announced that the Superconducting Super Collider (SSC) will soon be built somewhere in the United States. Preliminary geophysical studies indicate that the Sierrita site 35 miles southwest of Tucson has geological conditions that would facilitate construction of the SSC. The Maricopa site southwest of Phoenix is also one of the two potential sites in Arizona. However, several additional geotechnical investigations were required to convincingly demonstrate the suitability of these two locations. The present research program identified the geotechnical properties of the soils at the two sites through various levels of laboratory and field testing. The significance of these results are discussed and recommendations are given.