Statistical tests are performed on Project ARIES preliminary baseline measurements in the Southern California triangle formed by the Jet Propulsion Laboratory, the Owens Valley Radio observatory, and the Goldstone tracking complex during 1976--1980. In addition to conventional one-dimensional tests a two-dimensional test which allows for an arbitrary correlation between errors in individual components is formulated using the Hotelling statistic. On two out of three baselines the mean rate of change in baseline vector is statistically significant. Apparent motions on all three baselines are consistent with a pure shear with north-south compression and east-west expansion of 1¿10-7/year. The ARIES measurement are consistent with the USGS geodolite networks in Southern California and the SAFE laser satellite ranging experiment. All three experiments are consistent with a 6 cm/year motion between the Pacific and North American Plates and a band of diffuse shear 300 km wide, except that corresponding rotation of the entire triangle is not found.