We estimate the present-day vertical velocity field in the central Basin and Range and Sierra Nevada mountains and consider causative processes. We analyzed data from 16 continuously operating Global Positioning System stations finding that relative vertical velocity precision (WRMS scatter) is ∼0.25 mm/yr. These data demonstrate that the southern Sierra Nevada is experiencing uplift of ∼0.5 mm/yr relative to a local reference frame in southern Nevada, and ∼1 mm/yr relative to stations in the northern Mojave Desert. As a possible source of these motions, we explored post-seismic viscoelastic relaxation following the 1872 Owens Valley and 1952 Kern County earthquakes with models of laterally homogeneous lower crust and upper mantle viscosity. Post-seismic deformation from these two earthquakes cannot entirely explain the data set. Lateral variations in viscosity or contributions from other regional earthquakes may also be important.