GPS data define a broad zone of present day deformation in the eastern Basin and Range province, western US. Using finite element models with elastic upper crust over viscoelastic lower crust/upper mantle and incorporating earthquake cycle effects, we show that these data are consistent with a model whereby most contemporary fault slip is focused on the Wasatch fault zone. Modeled rates of horizontal extension are 3.0--4.5 mm/yr, in agreement with Holocene geologic data. The models are non-unique, in part because much of the Wasatch fault is in the late stages of the earthquake cycle, when surface velocity gradients across the fault are low.