The Pacific to Arizona Crustal Experiment (PACE) is a multidisciplinary transect which crosses an old magmatic arc, a continental rift, and an extensional terrane all located in southern California. The PIs will collect magnetotelluric data along this transect to enhance the seismic experiments already planned. Prominent mid-crustal refectors have already been found on CALCRUST lines in eastern California and COCORP lines in Arizona. Magnetotelluric soundings will be sensitive to these reflective zones if they are cause by fluid, partial melt, or conductive minerals such as graphite in mylonitic zones. Thus, electrical measurements will help identify midcrustal structure. Further, measurements in the Peninsular Ranges will help locate the old suture zone between continental and oceanic crust. The magnetotelluric survey will be contracted to a commercial contractor in order to guarantee the best data possible and will use the latest 2-D inversions and 3-D forward modeling to interpret the data. This survey is designed as a reconnaissance for a possible future EMSOC experiment.