The recent installation of a WWSSN station at El Paso, Texas (EPT), makes it possible to analyze Rayleigh wave dispersion along the axis of the Rio Grande rift. Analysis of dispersion along the path extending from El Paso, Texas, to Albuquerque, New Mexico (EPT-ALQ), indicates an average crustal thickness of approximately 32 km and an upper mantle shear wave velocity of approximately 4.25 km/s. This result is in agreement with recent seismic refraction studies in the area. Combined analysis of the dispersion and refraction data yields Poisson's ratios of 0.24, 0.27, and 0.29 in the upper crust, lower crust, and upper mantle, respectively. The observed phase velocities are very similar to those reported for the East African rift.