The region of central New Mexico where the Rio Grande rift begins to widen has been investigated via an integrated geological and geophysical analysis. Existing seismic refraction profiles and two seismic reflection profiles, when combined with gravity and drilling data, provide a good picture of basin geometry deep crustal structure in the region. The Palomas Basin is shown to be a half graben bounded by a listric-normal fault imaged by the seismic reflection data. The Engle Basin is also associated with a half graben. The structure of the Tularosa Basin is more symmetric with two grabens. An analysis of deeper structures indicates that the crust is 28 to 33 km thick in the rift with the greatest thickness being in the northern portion of the area.